Organic Laser Molecule with High Mobility, High Photoluminescence Quantum Yield, and Deep-Blue Lasing Characteristics

Article abstract of DOI:10.1021/jacs.0c00871

Here, we design and synthesize an organic laser molecule, 2,7-diphenyl-9H-fluorene (LD-1), which has state-of-the-art integrated optoelectronic properties with a high mobility of 0.25 cm² V^-1 s^-1, a high photoluminescence quantum yield of 60.3%, and superior deep-blue laser characteristics (low threshold of P_th = 71 μJ cm^-2 and P_th = 53 μJ cm^-2 and high quality factor (Q) of a?3100 and a?2700 at emission peaks of 390 and 410 nm, respectively). Organic light-emitting transistors based on LD-1 are for the first time demonstrated with obvious electroluminescent emission and gate tunable features. This work opens the door for a new class of organic semiconductor laser molecules and is critical for deep-blue optical and laser applications.

Full text of DOI:10.1021/jacs.0c00871

Subscriber access provided by NATIONAL UNIV OF SINGAPORE
Article
Organic laser molecule with high-mobility, high photolumines-
cence quantum yield and deep-blue lasing characteristics
Dan Liu, Jianbo De, Haikuo Gao, Suqian Ma, Qi Ou, Shuai Li, Zhengsheng Qin, Huanli Dong, Qing Liao, Bin
Xu, Qian Peng, Zhigang Shuai, Wenjing Tian, Hongbing Fu, Xiaotao Zhang, Yonggang Zhen, and Wenping Hu
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.0c00871 • Publication Date (Web): 18 Mar 2020
Downloaded from pubs.acs.org on March 18, 2020
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a service to the research community to expedite the dissemination
of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in
full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully
peer reviewed, but should not be considered the official version of record. They are citable by the
Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore,
the “Just Accepted” Web site may not include all articles that will be published in the journal. After
a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web
site and published as an ASAP article. Note that technical editing may introduce minor changes
to the manuscript text and/or graphics which could affect content, and all legal disclaimers and
ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or
consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W.,
Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 9
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
Organic laser molecule with high-mobility, high
photoluminescence quantum yield and deep-blue lasing
characteristics
Dan Liu,a,c Jianbo De,d Haikuo Gao,a,c Suqian Ma,e Qi Ou,f Shuai Li,d Zhengsheng Qin,a,c Huanli Dong,a,c* Qing Liao,d Bin Xu,e
Qian Peng,a Zhigang Shuai,f Wenjing Tian,e Hongbing Fu,d Xiaotao Zhang,b Yonggang Zhen,a and Wenping Hua,b
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
aBeijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy
of Sciences, Beijing 100190, China
bTianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University
and Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
cUniversity of Chinese Academy of Sciences, Beijing 100049, China
dBeijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Capital Normal University,
Beijing, 100048, China
eState Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, China
fDepartment of Chemistry, Tsinghua University, Beijing 100084, China
ABSTRACT: Here, we design and synthesize an organic laser molecule, 2,7-diphenyl-9H-fluorene (LD-1), which has the state-of-
the-art integrated optoelectronic properties with high mobility of 0.25 cm2 V-1 s-1, high photoluminescence quantum yield of 60.3 %
and superior deep-blue laser characteristics (low threshold of Pth = 71 uJ cm-2 and Pth = 53 uJ cm-2 and high quality factor (Q) of
~3100 and ~2700 at emission peaks of 390 nm and 410 nm, respectively). Organic light-emitting transistors based on LD-1 are for
the first time demonstrated with obvious electroluminescent emission and gate tunable features. This work opens the door for a new
class of organic semiconductor laser molecules, and is critical for deep-blue optical and laser applications.
 INTRODUCTION
mention simultaneously possessing good optical gain for
lasing character.8,9,30-32
Organic laser semiconducting molecules are the basis of
organic light emitting transistors (OLETs) and electrically
pumped organic laser (EPOLs), which demonstrate great
promise for smart display technology, organic lasers,
biosensing and other related optoelectronic circuits.1-5
However, it remains a big challenge for the development of
molecules for OLETs and EPOLs over the past decades.6-11
One of the key restrictive factors is the design motif
integrating high mobility, strong emission for efficient electro-
optic conversion, and ideal laser characteristics to achieve
sufficiently high number of excited states under high current
density to initiate lasing.8,9,12,13 Designing highly π-extended
fused conjugated systems is one effective approach to
increasing charge transport for high mobility,14-16 however,
such kind of molecules always show very weak fluorescence
in solid state due to the significant quenching of excited states
induced by condensed molecular packing and remarkable
singlet fissions.17,18 Reducing the π-conjugation and
intermolecular interactions enough may enhance the
fluorescence efficiency of organic materials, but generally at
the cost of efficient charge transport property.19-21 More
recently, achievement of high mobility emissive organic
semiconductor,22-26 high-efficiency OLETs6,7,27,28 and the
exciting indication of current-injection lasing from an organic
semiconductor29 have been demonstrated, which brings the
hope and passion of scientists from different fields to this field
research. Generally speaking, to date such materials are still
very limited, and only very few of them could meanwhile
possess the characteristic of amplified spontaneous emission
(ASE) phenomenon at reasonably low pump intensities, not to
Here, we design and synthesize a fluorene-based organic
semiconductor, 2,7-diphenyl-9H-fluorene (LD-1) (Figure 1a),
with efficient charge transport, strong emission as well as
superior lasing character. The molecule design concept of LD-
1 compound is as following: i) fluorene as the unit core is
intrinsically a superior building blocks for organic lasers;8,31 ii)
it is easily to get derivatives at 2,7 positions for extending π-
conjugation and modulating molecular arrangement to
enhance the charge transport; iii) it is also a promising
building block for designing blue emitting materials,33-35 which
is particularly important in displays and lasing but difficult to
be achieved, and finally iv) the introduction of rotational
carbon-carbon bond for extending π-conjugation could
modulate both optical and electrical properties for their good
integration.12,22-24,36 Indeed, experimental results demonstrate
that LD-1 compound well integrates the properties of high-
mobility charge transport and strong luminescence with carrier
mobility of 0.25 cm2 V-1 s-1 and photoluminescence quantum
yield (PLQY) of 60.3 % for its single crystals. Moreover,
deep-blue-emissive whispering-gallery-mode (WGM) laser is
demonstrated with a low threshold of 71 μJ cm-2 and 53 μJ cm-
2
and high cavity quality factor (Q) of 3100 and 2700 at
emission peaks of 390 nm and 410 nm, respectively. To our
knowledge, LD-1 is amongst the best performance of deep-
blue organic semiconductor laser integrating efficient charge
transport property reported in the literatures (Table S1, S2).
These attractive features of LD-1 make it be a good candidate
for the research of integrated optoelectronic devices.
 RESULTS AND DISCUSSION
ACS Paragon Plus Environment

Journal of the American Chemical Society
LD-1 was synthesized from 2,7-dibromofluorene and
Page 2 of 9
demonstrates that the LD-1 crystal belongs to orthorhombic
system with cell parameters of a = 5.8687 (2) Å, b = 33.6814
(8) Å, c = 8.4453 (3) Å (CCDC: 1942276 Table S3). As
indicated by single crystal data, a slight rotation angle of
26.01o and 14.00o is determined for the two π-extended
benzene rings (left and right) relative to the fluorene core due
to the rotation effect of C-C bond (Figure 1b), which is
beneficial for the reduce of fluorescence quenching effect.22-
1
2
3
4
5
6
7
8
phenylboronic acid using palladium-catalyzed Suzuki
coupling reaction with a high yield of 63 % (Scheme S1).
After vacuum-sublimation purification process, milky white
powder was obtained. Strong blue emission is easily observed
under UV light illumination in both cases of solution and
powder, giving a high PLQY of 65 % and 50 %, respectively
(Figure S1). The highest occupied molecular orbital (HOMO)
of -5.76 eV was calculated based on cyclic voltammetry (CV)
measurement curve (Figure S2), and the lowest unoccupied
molecular orbital (LUMO) of -2.72 eV was further calculated
based on the HOMO level and an energy band of 3.04 eV is
obtained from its UV-vis curves which will be shown in
following section. Good thermal stability of LD-1 with
24,36
Under the balance of C-C bond, good electron
distributions on the whole molecule at both HOMO and
LUMO levels are also demonstrated, which is favorable for
forming strong intermolecular interactions to achieve efficient
charge transport. A typical herringbone molecular packing
mode with a herringbone angle of 64.08° is adopted by LD-1
in single crystals where multi strong C–H–π interactions
(2.730-2.891 Å) between neighboring molecules are formed
(Figure S4). All the results suggest the capacity of LD-1 to
integrate strong fluorescence and efficient charge transport
properties together.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
o
sublimation temperature of 337 C was characterized from
thermal gravimetric analysis (TGA) (Figure S3). Large-sized
single crystals of LD-1 were obtained via a slow evaporation
process from the saturated mixture solution of CH2Cl2:ethanol
= 1:2 at room temperature. X-ray crystallographic data
Figure 1. (a) Chemical structure of LD-1 molecule and (b) the views of LD-1 molecule seeing perpendicular (top) to and along (side) the
conjugated plane of fluorene core. (c) Fluorescent image of LD-1 single crystals obtained through PVT technique. (d) XRD patterns of
LD-1 single crystals (inset is a schematic of the elongated hexagon LD-1 crystals with the indexed diffraction planes according to structure
analysis). (e) TEM image of an individual crystal and its corresponding SAED pattern. Scale bar: 2 μm. (f) Two-dimensional charge
transport routes in LD-1 crystals with herringbone molecular packing.
To further investigate the charge transport and optical property
of LD-1, high-quality micro/nano-single crystals of LD-1 were
prepared by physical vapor transport (PVT). Slightly-
elongated hexagon LD-1 crystals with a side-length (W1 (long
edges)/W2 (short edges)) ratio centered at around 1.8 based on
100 crystals were usually obtained (Figure S5), which have
ACS Paragon Plus Environment

Page 3 of 9
Journal of the American Chemical Society
smooth surface (root mean square (RMS): 0.789 nm) and
(SAED) pattern, which was taken by directing the electron
beam perpendicular to the flat surface of individual LD-1
single crystal. The bright and strong multi-order diffraction
peaks further confirm the high crystallinity of LD-1
micro/nano-crystals. Based on the LD-1 crystal cell
parameters, the spots in the white square and green circle can
be ascribed to the Bragg reflections of (001) and (100) planes
with d(001) = 8.46 Å and d(100) = 5.93 Å, respectively.
Combining XRD and SAED results together, a schematic of
LD-1 crystal planes in hexagon morphology is shown in inset
1
2
3
4
5
6
7
8
thickness of around 100 nm characterized by atomic force
microscopy (AFM) (Figure S6). A high PLQY of 60.3% was
determined for single crystals of LD-1 (Figure 1c), which is
slightly lower than that of LD-1 in solution due to the
aggregation effect but still maintain the strong emission
characteristic, even in single crystal state. Under 330-380 nm
light illumination, typical optical waveguide feature was
observed for LD-1 crystals with a manifestation of very bright
emission from their crystal edges suggesting the high quality
of the obtained LD-1 crystals, which is a crucial parameter for
high optical gain to initiate lasing. Figure 1d shows the X-ray
diffraction (XRD) patterns of LD-1 micro/nano-crystals grown
on Si/SiO2 substrate where a series of very sharp and strong
diffraction peaks were observed. These diffraction peaks could
be well indexed by (0k0) reflections based on single crystal
data of LD-1, giving a layer-by-layer growth mode along b-
axis with a interlayer d-spacing of 33.94 Å, indicating that the
long axis of LD-1 molecule is nearly standing on the substrate
(Figure S7a). Figure 1e shows the transmission electron
microscopy (TEM) image of an individual LD-1 single crystal
and its corresponding selected area electron diffraction
9
1
of Figure 1d, where the crystals (010) and (0 0) crystal planes
are on the top and bottom bound by (002), (00 ), ( 01), (10 ),
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
2
1
1
1 1
2
(101) and ( 0 ) crystal planes on the six side-faces, ∠(00 )/
1
1
∠(10 ) = 125°, ∠(10 )/
∠(101) = 110° (Figure S7b). As
shown in Figure 1f, an efficient two-dimensional charge
transport network is formed in direction of ac planes, which is
parallel to the substrate. In this case, if one molecule gains a
charge, it can quickly transfer to the two neighbors, and then
onto the surrounding molecules, forming a two-dimensional
network, which would ensure high mobility in planar organic
field-effect transistors (OFETs).14,37
Figure 2. (a) UV-vis absorption, PL and ASE (filled area) spectra for the LD-1 in CH2Cl2 solution and crystals. (b) CIE 1931
coordinates of the LD-1 crystals. (c) Time-resolved peak fluorescence of LD-1 in CH2Cl2 solution and crystals. (d) Schematic graph
of the 4-energy level of LD-1 molecule and the HOMO and LUMO in crystals.
The photophysical properties of LD-1 in solution and single
crystal state were systematically investigated. Figure 2a
shows the UV-vis absorption and photoluminescence (PL)
spectra of LD-1 in dichloromethane (CH2Cl2) solution (dashed
lines) and crystals (solid lines) as well as the amplified
spontaneous emission (ASE) spectra of LD-1 crystals. Key
photophysical parameters measured for LD-1 are summarized
in Table 1. A high molar absorption coefficient of 4.4×104
M−1 cm−1 at 323 nm was determined for LD-1 in dilute CH2Cl2
solution, a primary parameter ensuring for its strong emission.
In comparison with that of solution absorption, an obvious
bathochromic-shift with the main peaks located at 353 nm is
demonstrated for LD-1 crystals, which is one indication of J-
aggregation in crystals. PL spectra demonstrate that the main
ACS Paragon Plus Environment

Journal of the American Chemical Society
emission peak of LD-1 crystal is red-shifted to 407 nm,
Page 4 of 9
(Figure 2a and Figure S8). A narrowed bandwidth of PL
spectrum with a half-maximum (FWHM) of 9.66 nm was
observed for LD-1 crystals and a sharp ASE peak is located at
407 nm, which is well consistent with that of its PL spectrum.
A threshold energy of 168 uJ cm-2, high gain coefficient (48
cm−1), and low loss coefficient (5.29 cm−1) were further
characterized based on the deep investigations at the ASE
peak (Figure S9). In addition, according to the theoretical
calculation (Figure 2d, Figure S10 and Table S5), a well-
separated four-energy level is formed between the ground state
S0 and the first excited state S1. Consisting of 96.6 % local
transition from the HOMO to the LUMO, S1 is a highly
luminescent state with a calculated transition dipole moment
larger than 12 Debye. After being excited to S1 state, the
molecule will immediately relax to the lowest vibrational level
of S1 (E3). Spontaneous and stimulated emission will then take
place from E3 to E2, followed by another immediate
vibrational relaxation process to E1. This four-energy level
system guarantees that more luminophores populates on the E3
than E2. A large Stokes shift is observed in both the spectra
and the four-energy level graph. All the results demonstrate
that LD-1 is a superior deep-blue organic semiconductor with
very strong emission, good optical waveguide emission and
ASE property for organic solid-state laser.
1
2
3
4
5
6
7
8
suggesting LD-1 is a deep- blue emission semiconductor. As
we know that, it still remains an urgent task to develop high
performance deep-blue emissive organic semiconductors
though it is great crucial in organic optoelectronic devices.
According to the National Television Standards Committee
(NTSC), the calculated Commission Internationale de
l'Éclairage (CIE) coordinates of LD-1 are (0.16, 0.07) (Figure
2b), which are very close to the standard blue CIE coordinates
of (0.14, 0.08), suggesting LD-1 is also one of the very few
blue emissive organic semiconductors reported so far.38-40 The
superior deep-blue character of LD-1 with CIE y < 0.10
suggests its great potential for blue optical and laser
applications. The time-resolved fluorescence spectra shown in
Figure 2c reveals the reduced fluorescence lifetime (τ) for
LD-1 crystals (1.90 ns) compared to that of its CH2Cl2 solution
(2.83 ns) when fitted by a double-exponential decay model
(Table S4). Correspondingly, fast radiative deactivation rates
(kr = ΦF/τFL) of 3.16×108 s-1 and 2.30×108 s-1 are determined
for LD-1 in crystals and solution, respectively, suggesting the
efficient emission of LD-1 both in solution and crystals.
Typical ASE property was further characterized for LD-1
single crystals when using a 355 nm pulsed laser as the
excitation source along with increase of the pulse energy
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Table 1. A summary of photophysical properties of LD-1 in CH2Cl2 solution and crystals.
a,b
LD-1
In solution
crystals
λabsa [nm]
307 323
353
εmaxa [M−1 cm−1]
λema [nm]
356 368
407
ΦF
τFLc [ns]
2.83
krd [s-1]
2.30×108
3.16×108
knre [s-1]
1.24×108
2.11×108
4.4×104
0.65
0.60
1.90
—
In CH2Cl2 solution (1 × 10−5 M). ΦF of the absolute photoluminescence quantum yield (PLQY) via using the integrating sphere.
Fluorescence lifetime. Radiative deactivation rate calculated according to the kr = ΦF/τFL equation. Non-radiative deactivation rate
calculated according to the knr = 1/τFL - kr equation.
a
b
c
d
e
Encouraged by the above results, we further investigated the
lasing characteristics of LD-1 crystals (Figure 3). Obviously,
two main lasing peaks located at 390 nm and 410 nm were
evolved in the PL spectra along with increasing the pulse
density (Figure S11), demonstrating a multi-mode lasing
characteristic as evidenced by the high-resolution PL spectra
shown in Figure 3a and Figure 3d. As can be seen that the
two PL spectra display a broad spontaneous emission at low
pump density excitation when the pump density exceeds the
threshold (Pth) of 71 uJ cm-2 at 390 nm and Pth = 53 uJ cm-2 at
410 nm, respectively (Figure 3b and Figure 3e), a set of sharp
peaks merging on the top of spontaneous emission spectra. In
addition, the intensity dependence is fitted according to the
power law xp equation.41 The latter p = 2.99 ± 0.15 (390 nm)
and p = 1.85 ± 0.05 (410 nm) above the threshold were further
calculated, indicating a superlinear regime with typical
characteristic of laser emission. As shown in the left inset of
Figure 3b, the strong deep-blue laser emission occurs on the
top four edges of LD-1 single crystal, indicating that the LD-1
single crystal can act as an efficient 2D micro-resonator of
whispering-gallery-mode (WGM). It could be deduced that the
light was totally reflected by the four edges and transported
along an oblong route in the crystal as shown in inset of
Figure 3e. To confirm the WGM micro-resonator, the
dependence of the spacing between adjacent modes (Δλ) on
optical path length (L) of LD-1 single crystals were further
characterized (Figure 3g). Clearly, the mode spacing Δλ
gradually decreases and exhibits more and more modes with
the increase of the optical path length L. Specifically, Δλ390
=
0.73, 0.59, and 0.48 nm were observed for length L = 17, 23,
and 30 μm at emission peak of 390 nm, and similar
phenomenon was also observed for lasing emission peak at
410 nm with Δλ410 = 1.11, 0.91, and 0.78 nm for length L = 17,
23, and 30 μm. Such evolution between Δλ and length L well
corresponds to the characteristic of WGM cavity.42,43 To
further understand the resonant mode and the relationship of
WGM cavity and mode spacing, the following the equation is
used:
λ2
Δλ =
퐿[푛 ― 휆(푑푛/푑휆)]
where Δλ is the spacing between adjacent modes (Figure S12),
[n – λ(dn/dλ)] is the group refractive index,42,43 according to
geometric conditions, the optical path length (L) within the
resonator could be expressed as
L = 2 (W1 + W2 × Sin55°)
where W1 and W2 are the edge lengths of the LD-1 single
crystal (inset image in Figure 1d). The linear increase of Δλ
along with that of increasing 1/L further confirms the
formation of WGM-mode cavity for both the two lasing peaks
of 390 nm and 410 nm (Figure 3h). In addition, the cavity
ACS Paragon Plus Environment

Page 5 of 9
Journal of the American Chemical Society
quality factor, another important lasing parameter is also
which are well consistent with that of simulated Q values of
3088 at 390 nm and 2600 at 410 nm (Figure 3c and Figure
3f). Furthermore, LD-1 single crystals demonstrated good
lasing stability during our experimental measurement, which is
important for its potential applications.
1
2
3
4
investigated with the equation of Q = λ/ΔλL, where λ is the
lasing peak wavelength and ΔλL is the FWHM of the lasing
peak (Figure S12), a significant parameter to evaluate a laser
micro-cavity.44 Very high experimental Q factors of ∼3100 at
390 nm and ∼2700 at 410 nm were obtained (Table S6),
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 3. High-resolution PL spectra of the laser emission around 390 nm (a) and 410 nm (d) under different pump densities. (b)
Integrated area of the peak 390 nm as a function of pump density. The lasing threshold is identified as the intersection between the
sublinear and superlinear regions. Inset: forth bright PL edges of the LD-1 single crystal under 355 nm fs laser excitation. (e) Integrated
area of the peak (410 nm) as a function of pump density. Inset: illustrate a typical optical-ray analysis within WGM- LD-1 microcavity.
Optical mode simulation results for a LD-1 single crystal with W1 = 18 μm and W2 = 9 μm, Q = 3088 of λ = 390 nm (c) and Q = 2600 of λ
= 410 nm (f). (g) High resolution PL spectra of laser emission recorded above the threshold for LD-1 with L = 17, 23, and 30 μm. (h)
Mode spacing Δλ at λ = 390 nm and 410 nm versus 1/L of the LD-1 crystals, showing a clear linear relationship.
Furthermore, the charge transport property of LD-1 was
investigated based on organic field-effect transistors (Figure
S13). Due to the extension of π-conjugation in LD-1
compound ensuring strong intermolecular couplings, efficient
electrical transporting property was confirmed for LD-1 with
the saturation charge carrier mobility up to 0.25 cm2 V-1 s-1
calculated from the typical transfer curves of organic field-
as the emitting layer and N,N'-Bis (naphthalen-1-yl) -N,N'-bis
(phenyl)-benzidine (NPB) is hole injection layer and (3,3'-[5'-
[3-(3-Pyridinyl)phenyl][1,1':3',1''-terphenyl]-3,3''-
diyl]bispyridine) (TmPypB) is electron injection layer,
respectively. A vertical OLET structure was adopted here with
the consideration of its intrinsically short conducting channel
for high current density and feasible incorporation of optical
configuration and distributed feedback geometry for efficient
electroluminescence performance and or initiating lasing.3,45
Figure 4b shows the energy alignment of NPB, LD-1,
TmPypB and the source electrode of graphene. Due to the
tunable Fermi level of graphene and thus the Schottky barrier
between bottom graphene and NPB hole injection layer under
negative and positive gate voltages, the OLET device can be
operated in the on and off states (Figure S16). Furthermore,
using other typical electron transporting material, 1,3,5-tris(2-
N-phenylbenzimidazolyl)benzene (TPBi) replace of TmPypB,
another device structure of Si/ SiO2/ Graphene (Gate)/
NPB/LD-1/TPBi/LiF/Al/Ag was also constructed in the
effect transistors according to the equation of IDS
=
(μWCi/2L)(VG - VT)2 (Figure S14) which is more than one
order of magnitude higher than that previously reported for
fluorene-based organic laser semiconductors (Figure S15 and
Table S2). The integration of superior optical and electrical
transport properties for LD-1 compound (as summarized in
Table 2) ensures its application in integrated optoelectronic
device. As an example, OLET, which is possibly the
minimized integrated optoelectronic device and also one of the
promising device structures for study of EPOLs was further
investigated. Figure 4a shows the schematic image of LD-1-
based OLET where vacuum-deposited LD-1 thin film is used
ACS Paragon Plus Environment

Journal of the American Chemical Society
experiment. These two devices demonstrated similar
Page 6 of 9
relative intensity for emission peaks, probably due to the
complex effects induced by different molecular packing
structures, optical resonator effect and interface effect in the
electrically-driven electroluminescent devices. In addition,
compared to molecules in solution,46 LD-1 molecules in single
crystal state show relatively good stability under both
electrical field and 355 nm pulse laser, which is important for
potential device applications. More deep research works are
still needed in future with the emphasis of constructing
appropriate device geometry with optimized molecular
packing structure, high quality interface contact, integration of
photonic structure and pumping the devices with electrical
pulse signal.29,47-51
1
2
3
4
5
6
7
8
electroluminescence phenomenon with strong emission.
Typical electrical and optical output characteristics of LD-1
OLETs (Figure 4c) demonstrate a clear and consistent
correlation between the current density and emitting light
output power, suggesting the good tunability of such device
under applied gate voltages. When applied VDS of –20 V and
VGS of -60 V, a current density of around 32 mA cm-2 was
obtained and strong blue electroluminescence was observed as
shown in Figure 4d with uniform emitting character on the
overall active region. The intensity of electroluminescence
spectra could be obviously increased along with the increase
of negative VG (Figure S17), which is consistent with that of
PL spectrum of LD-1 thin films (Figure S18) with different
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 4. (a) Schematic of LD-1 based OLET device. (b) Energy level diagram of graphene, NPB, LD-1, TmPypB and the
thickness of each layer used in the device. (c) Typical optical and electrical output characteristics of LD-1 OLET. (d) The color-
coded images of LD-1-OLET extracted from light emission captured by CCD.
Table 2. Key optoelectronic properties of LD-1 compound in single crystal state.
Mobility
Laser
λabs
[nm]
λem
[nm]
λASE
[nm]
Gain
Loss
Pth
VT
[V]
Material
PLQY
Q
[cm2 V-1
s-1]
Ion/off
[cm−1]
[cm−1]
[uJcm-2]
ACS Paragon Plus Environment

Page 7 of 9
Journal of the American Chemical Society
71
[390 nm]
53
[410 nm]
3100
[390 nm]
2700
1
2
3
4
5
6
7
8
106
LD-1
353
407
60.3 %
407
48
5.29
0.25
6
[410 nm]
organic light-emitting transistors for active matrix Displays.
Science. 2011, 332, 570-573.
Capelli, R.; Toffanin, S.; Generali, G.; Usta, H.; Facchetti, A.;
Muccini, M. Organic light-emitting transistors with an
efficiency that outperforms the equivalent light-emitting diodes.
Nat. Mater. 2010, 9, 496-503.
Hou, L. L.; Zhang, X. Y.; Cotella, G. F.; Carnicella, G.; Herder,
M.; Schmidt, B. M.; Pätzel, M.; Hecht, S.; Cacialli, F.; Samorì,
P. Optically switchable organic light-emitting transistors. Nat.
Nanotech. 2019, 14, 347-353.
Zhang, C.; Chen, P.; Hu, W. Organic light-emitting transistors:
materials, device configurations, and operations. Small 2016,
12, 1252-1294.
 CONCLUSIONS
In conclusion, an organic laser molecule, LD-1 was designed
and synthesized by introducing phenyl units into the emissive
fluorene core via a rotational carbon-carbon bond. Efficient
charge transport with carrier mobility of 0.25 cm2 V-1 s-1 and
strong solid-state emission with PLQY of 60.3 % are
demonstrated. Moreover, its single crystals exhibit unique
ASE phenomenon with outstanding deep-blue laser character
of low thresholds of 71 μJ cm-2 and 53 μJ cm-2 and high
quality (Q) factor of ~3100 and ~2700 at emission peaks of
390 nm and 410 nm, respectively by WGM resonator. As an
example of LD-1 in integrated optoelectronic device
application, OLET based on LD-1 was demonstrated. The
importance of this work is that i) we present a superior organic
optoelectronic compound, LD-1, that well simultaneously
4.
5.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
6.
7.
Liu, C. F.; Liu, X.; Lai, W. Y.; Huang, W. Organic light-
emitting field-effect transistors: device geometries and
fabrication techniques. Adv. Mater. 2018, 30, 1802466.
Samuel, I. D. W.; Turnbull, G. A. Organic semiconductor
lasers. Chem. Rev. 2007, 107, 1272-1295.
8.
9.
integrates
high
charge
carrier
mobility,
strong
Tessler, N. Lasers based on semiconducting organic materials.
Adv. Mater. 1999, 11, 363-370.
photoluminescence, excellent lasing character as well as rare
and commendable deep-blue optical property; ii) it opens a
door for further developing a series of more efficient organic
laser semiconductor towards compact, low-cost display and
laser technology. More systematic research works are on-
going and we believe much higher performances would be
expected in future by further rational molecular design and
device optimization.
10. Bradley, D. D. C. Organic electronics and photonics:
concluding remarks. Faraday. Discuss. 2014, 174, 429-438.
11. Lin, J.; Hu, Y.; Lv, Y.; Guo, X.; Liu, X. Light gain
amplification in microcavity organic semiconductor laser
diodes under electrical pumping. Sci. Bull. 2017, 62, 1637-
1638.
12. Zhang, X.; Dong, H.; Hu, W. Organic semiconductor single
crystals for electronics and photonics. Adv. Mater. 2018, 30,
1801048.
13. Ma, Y. G.; Shen, J. C. Research progress of photoelectric
functional organic crystals. Sci. China Ser. B. 2007, 37, 105-
123.
14. Dong, H.; Fu, X.; Liu, J.; Wang, Z.; Hu, W. 25th Anniversary
article: key points for high-mobility organic field-effect
transistors. Adv. Mater. 2013, 25, 6158-6183.
ASSOCIATED CONTENT
Supporting Information.
Experimental details, synthesis, characterization, device
fabrication, and theoretical studies (PDF). The Supporting
Information is available free of charge on the ACS Publications
website.
15. Wadsworth, A.; Chen, H.; Thorley, K. J.; Cendra, C.; Nikolka,
M.; Bristow, H.; Moser, M.; Salleo, A.; Anthopoulos, T. D.;
AUTHOR INFORMATION
Sirringhaus,
H.;
McCulloch,
I.
Modification
of
Corresponding Author
indacenodithiophene-based polymers and its impact on charge
carrier mobility in organic thin-film transistors. J. Am. Chem.
Soc. 2020, 142, 652-664.
*dhl522@iccas.ac.cn
16. Ni, Z. J.; Wang, H. L.; Dong, H. L.; Dang, Y. F.; Zhao, Q.;
Zhang, X. T.; Hu, W. P. Mesopolymer synthesis by ligand-
modulated direct arylation polycondensation towards n-type
and ambipolar conjugated systems. Nat. Chem. 2019, 11, 271-
277.
17. Anthony, J. E.; Brooks, J. S.; Eaton, D. L.; Parkin, S. R.
Functionalized pentacene:ꢀ improved electronic properties from
control of solid-state order. J. Am. Chem. Soc. 2001, 123, 9482-
9483.
18. Zimmerman, P. M.; Bell, F.; Casanova, D.; Head-Gordon, M.
Mechanism for singlet fission in pentacene and tetracene: from
single exciton to two triplets. J. Am. Chem. Soc. 2011, 133,
19944-19952.
19. Grimsdale, A. C.; Chan, K. L.; Martin, R. E.; Jokisz, P. G.;
Holmes, A. B. Synthesis of light-emitting conjugated polymers
for applications in electroluminescent devices. Chem. Rev.
2009, 109, 897-1091.
20. Huang, Y. J.; Wang, Z. R.; Chen, Z.; Zhang, Q. C. Organic
cocrystals: beyond electrical conductivities and field-effect
transistors (FETs). Angew. Chem. Int. Ed. 2019, 58, 9696-9711.
21. Mei, J.; Leung, N. L. C.; Kwok, R. T. K.; Lam, J. W. Y.; Tang,
B. Z. Aggregation-induced emission: together we shine, united
we soar, Chem. Rev. 2015, 115, 11718-11940.
22. Liu, J.; Zhang, H.; Dong, H.; Meng, L.; Jiang, L.; Jiang, L.;
Wang, Y.; Yu, J.; Sun, Y.; Hu, W.; Heeger, A. J. High mobility
emissive organic semiconductor. Nat. Commun. 2015, 6, 10032.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENT
The authors acknowledge the financial support from the Ministry
of Science and Technology of China (2017YFA0204503,
2018YFA0703200, 2016YFB0401100), the National Natural
Science Foundation of China (51725304, 61890943, 91833306,
51733004, 21875259, 51633006), Beijing National Laboratory for
Molecular Sciences (BNLMS- CXXM-202012), the Youth
Innovation Promotion Association of the Chinese Academy of
Sciences and the National Program for Support of Top-notch
Young Professionals.
REFERENCES
1.
Muccini, M.; Toffanin, S. Organic light-emitting transistors:
towards the next generation display technology, Wiley-Science
Wise Co-Publication, Hoboken, NJ, USA 2016.
Mnccini, M. A bright future for organic field-effect transistors.
Nat. Mater. 2006, 5, 605-613.
2.
3.
McCarthy, M. A.; Liu, B.; Donoghue, E. P.; Kravchenko, I.;
Kim, D. Y.; So, F.; Rinzle, A. G. Low-voltage, low-power,
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 8 of 9
23. Li, J.; Zhou, K.; Liu, J.; Zhen, Y.; Liu, L.; Zhang, J.; Dong, H.;
36. Xie, Z. Y.; Liu, D.; Zhang, Y. H.; Liu, Q. Q.; Dong, H. L.; Hu,
W. P. Recent advances on high mobility emissive anthracene-
derived organic semiconductors. Chem. Res. Chin. Univ. 2020,
accepted.
37. Wang, L.; Nan, G.; Yang X.; Peng, Q.; Li, Q.; Shuai, Z.
Computational methods for design of organic materials with
high charge mobility. Chem. Soc. Rev. 2010, 39, 423–434.
38. Xing, X.; Zhang, L.; Liu, R.; Li, S.; Qu, B.; Chen, Z.; Sun, W.;
Zhang, X.; Jiang, L.; Hu, W. Aromatic extension at 2,6-
positions of anthracene toward an elegant strategy for organic
semiconductors with efficient charge transport and strong solid
state emission. J. Am. Chem. Soc. 2017, 139, 17261-17264.
24. Chen, M.; Zhao, Y.; Yan, L.; Yang, S.; Zhu, Y.; Murtaza, I.;
He, G.; Meng, H.; Huang, W. A unique blend of 2-Fluorenyl-2-
anthracene and 2-Anthryl-2anthracence showing white
emission and high charge mobility. Angew. Chem. Int. Ed.
2017, 56, 722–727.
25. Liu, D.; Li, J.; Liu, J.; Lu, X.; Hu, M.; Li, Y.; Shu, Z.; Ni, Z.;
Ding, S.; Jiang, L.; Zhen, Y.; Zhang, X.; Dong, H.; Hu, W. A
new organic compound of 2-(2,2-diphenylethenyl)anthracene
(DPEA) showing simultaneous electrical charge transport
property and AIE optical characteristics. J. Mater. Chem. C
2018, 6, 3856-3860.
26. Deng, J.; Xu, Y.; Liu, L.; Feng, C.; Tang, J.; Gao, Y.; Wang, Y.;
Yang, B.; Lu, P.; Yang, W.; Ma, Y. An ambipolar organic field-
effect transistor based on an AIE-active single crystal with a
high mobility level of 2.0 cm2 V-1 s-1. Chem. Commun. 2016, 52,
2370-2373.
27. Qin, Z. S.; Gao, H. K.; Liu, J.; Zhou, K.; Li, J.; Dang, Y. Y.;
Huang, L.; Deng, H. X.; Zhang, X, T.; Dong, H. L.; Hu, W. P.
High-efficiency single-component organic light-emitting
transistors. Adv. Mater. 2019, 31, 1903175.
1
2
3
4
5
6
7
8
Xiao, L.; Gong, Q.
A deep-blue emitter with electron
transporting Property to improve charge balance for organic
light-emitting device. ACS Appl. Mater. Interface 2012, 4,
2877-2880.
9
39. Kim, Y. H.; Shin, D. C.; Kim, S. H.; Ko, C. H.; Yu, H. S.; Chae,
Y. S.; Kwon, S. K. Novel blue emitting material with high
color purity. Adv. Mater. 2001, 13, 1690-1693.
40. Gao, Z.; Li, Z.; Xia, P.; Wong, M.; Cheah, K. W.; Chen, C. H.
Efficient deep-blue organic light-emitting diodes: arylamine-
substituted oligofluorenes. Adv. Funct. Mater. 2007, 17, 3194–
3199.
41. Kena-Cohen, S.; Forrest, S. R. Room-temperature polariton
lasing in an organic single-crystal microcavity. Nat. Photon.
2010, 4, 371-375.
42. Wang, X.; Liao, Q.; Kong, Q.; Zhang, Y.; Xu, Z.; Lu, X.; Fu,
H. Whispering-gallery-mode microlaser based on self-
assembled organic single-crystalline hexagonal microdisks.
Angew. Chem. Int. Ed. 2014, 53, 5863-5867.
43. Yu, Z.; Wu, Y.; Liao, Q.; Zhang, H.; Bai, S.; Li, H.; Xu, Z.; Sun,
C.; Wang, X.; Yao, J.; Fu, H. Self-assembled microdisk lasers
of perylenediimides. J. Am. Chem. Soc. 2015, 137, 15105-
15111.
44. Wang, X.; Li, H.; Wu, Y.; Xu, Z.; Fu, H. Tunable morphology
of the self-assembled organic microcrystals for the efficient
laser optical resonator by molecular modulation. J. Am. Chem.
Soc. 2014, 136, 16602-16608.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
28. Oh, S.; Kim, J. H.; Park, S. K.; Ryoo, C. H.; Park, S. Y.
Fabrication of Pixelated Organic light-emitting transistor
(OLET) with a pure red‐emitting organic semiconductor. Adv.
Opt. Mater. 2019, 7, 1901274.
29. Sandanayaka1, A. S. D.; Matsushima, T.; Bencheikh, F.;
Terakawa, S.; Potscavage, J. W. J.; Qin, C.; Fujihara, T.;
Goushi, K.; Ribierre, J. C.; Adachi, C. Indication of current-
injection lasing from an organic semiconductor. Appl. Phys.
Express. 2019, 12, 061010.
45. Ma, L.; Yang Y. Unique architecture and concept for high
performance organic transistors. Appl. Phys. Lett. 2004, 85, 21-
22.
46. Kobin, B.; Behren, S.; Braun-Cula, B.; Hecht, S. Photochemical
degradation of various bridge-substituted fluorene based
materials. J. Phys. Chem. A 2016, 120, 5474-5480.
30. Wang, K.; Gao, Z. H.; Zhang, W.; Yan, Y. L.; Song, H. W.;
Lin, X. Q.; Zhou, Z. H.; Meng, H. B.; Xia, A. D.; Yao, J. N.;
Zhao, Y. S. Exciton funneling in light-harvesting organic
semiconductor microcrystals for wavelength-tunable lasers, Sci.
Adv. 2019, 5, eaaw2953.
31. Yap, B. K.; Xia, R.; Campoy-Quiles, M.; Stavrinou, P. N.;
Bradley, D. D. C. Simultaneous optimization of charge-carrier
mobility and optical gain in semiconducting polymer films. Nat.
Mater. 2008, 7, 376-380.
32. Ma, S.; Zhou, K.; Hu, M.; Li, Q.; Liu, Y.; Zhang, H.; Jing, J.;
Dong, H.; Xu, B.; Hu, W.; Tian W., Integrating efficient optical
gain in high-mobility organic semiconductors for
multifunctional optoelectronic applications. Adv. Funct. Mater.
2018, 28, 1802454.
33. Wei, Q.; Li, Y.; Liu, J.; Fang, Q.; Li, J.; Yan, X.; Xie, L.; Qian,
Y.; Xia, R.; Huang, W. A high performance deep blue organic
laser gain material. Adv. Opt. Mater. 2017, 5, 1601003.
34. Qian, Y.; Wei, Q.; Del Pozo, G.; Mroz, M. M.; Lueer, L.;
Casado, S.; Cabanillas-Gonzalez, J.; Zhang, Q.; Xie, L.; Xia,
R.; Huang, W. H-Shaped oligofluorenes for highly air-stable
and low-threshold non-doped deep blue lasing. Adv. Mater.
2014, 26, 2937-2942.
47. Samuel, D. W.; Namdas, E. B.; Turnbull, G. A. How to
recognize lasing. Nat. Photon. 2009, 3, 546-549
48. Gwinner, M. C.; Khodabakhsh, S.; Song, M. H.; Schweizer, H.;
Giessen, H.; Sirringhaus, H. Integration of a rib waveguide
distributed feedback structure into a light-emitting polymer
field-effect transistor. Adv. Funct. Mater. 2009, 19, 1360-1370.
49. Namdas, E. B.; Tong, M.; Ledochowitsch, P.; Mednick, S. R.;
Yuen, J. D.; Moses, D.; Heeger, A. J. Low thresholds in
polymer lasers on conductive substrates by distributed feedback
nanoimprinting: progress toward electrically pumped plastic
lasers. Adv. Mater. 2009, 21, 799-802.
50. Bisri, S. Z.; Takenobu, T.; Sawabe, K.; Tsuda, S.; Yomogida,
Y.; Yamao, T.; Hotta, S.; Adachi, C.; Iwasa, Y. p-i-n
homojunction in organic light-emitting transistors. Adv. Funct.
Mater. 2009, 19, 1360–1370.
51. Hotta, S. Optically and electrically excited emissions from
organic semiconducting oligomer crystals. Polym. Int. 2017, 66,
223-236.
35. Schneider, D.; Rabe, T.; Riedl, T.; Dobbertin, T.; Werner, O.;
Kroger, M.; Becker, E.; Johannes, H. H.; Kowalsky, W.;
Weimann, T.; Becker, J.; Hinze, P.; Gerhard, A.; Stossel, P.;
Vestweber, H. Deep blue widely tunable organic solid-state
laser based on a spirobifluorene derivative. Appl. Phys. Lett.
2004, 84, 4693-4695.
ACS Paragon Plus Environment

Page 9 of 9
Journal of the American Chemical Society
TOC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
9
ACS Paragon Plus Environment