Fabrication and characteristics of fullerene-perylene dyad based organic photovoltaic cell

Article abstract of DOI:10.1166/jnn.2011.3701

Fullerene is an acceptor material which is used most usually in organic photovoltaic cell. By the way, the reduction of electron mobility and the phase separation of conducting polymer and fullerene in the actual bulk heterojunction photovoltaic cell limi

Full text of DOI:10.1166/jnn.2011.3701

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Journal of
Nanoscience and Nanotechnology
Vol. 11, 4644–4647, 2011
Fabrication and Characteristics of Fullerene–Perylene
Dyad Based Organic Photovoltaic Cell
Byoung Min So1, Chan Moon Chung2, and Se Young Oh1ꢀ∗
1Department of Chemical & Biomolecular Engineering, Sogang University, Seoul 121-742, Korea
2Department of Chemistry, Yonsei University, Wonju, Kangwon-do 220-710, Korea
Fullerene is an acceptor material which is used most usually in organic photovoltaic cell. By the way,
the reduction of electron mobility and the phase separation of conducting polymer and fullerene
in the actual bulk heterojunction photovoltaic cell limit further improvement of device performance.
In order to overcome the problems, fabrication of hybrid planar mixed heterojunction cells and
synthesis of donor–acceptor dyadDheavlievbeereedn sbtyudIiendg.eInntathetop:resent work, we have synthesized
fullerene–perylene dyad to improve the fullerene based photovoltaic cell. In order to explore the
University of South Australia
properties of the synthesized material, the measurements of absorption spectrum and energy level
IP : 95.24.27.4
were carried out. We have investigated the energy conversion efficiency of organic photovoltaic cell
Tue, 18 Sep 2012 11:58:43
consisting of ITO/PEDOT-PSS/MEH-PPV:fullerene–perylene dyad/Al.
Keywords: Photovoltaic Cell, MEH-PPV, Fullerene–Perylene Dyad, Energy Conversion
Efficiency.
1. INTRODUCTION
derivative material that solubility and electron mobility
was improved. Also, synthesis of donor–acceptor dyad
based on fullerene has been carried out.12 Reduction of
electron mobility in bulk heterojunction structure was con-
firmed by Förrest et al.13ꢀ14 Planar mixed hetero junction of
D/D+A/A structure has designed to overcome the reduc-
tion problem.
In the present work, we have synthesized fullerene
derivative (FP) containing perylene moiety that has high
electron mobility, electron acceptor property and optical
activity. And then, physical and electrical properties of
synthesized FP were investigated with UV-Visible, cyclic-
voltammetry and current–voltage source meters. We have
investigated the energy conversion efficiency of organic
photovoltaic cells consisting of ITO/PEDOT-PSS/MEH-
PPV:FP/Al under various FP contents.
Organic photovoltaic cells have attracted considerable
attention due to their potential for low cost solar energy
conversion.1–6 Since donor–acceptor (D–A) heterojunction
organic photovoltaic cell having 0.95% efficiency using
copper phthalocyanine and perylene tetracarboxylic deriva-
tive was reported by Tang et al., the power conversion
efficiency has steadily improved through the develop-
ment of new materials and device structures.7ꢀ8 The dis-
covery of ultrafast photoinduced charge transfer from
conducting polymer to Buckminsterfullerene C60 has pro-
moted research towards high efficiency organic photo-
voltaic cells.9–11 Actually, the structure of fullerene is
favorable to serve as a strong electron acceptor in both
ground and excited states. However, the low solubil-
ity in most solvent, the reduction of electron mobility
and the phase separation formed in the bulk heterojunc-
tion photovoltaic devices using conducting polymer and
fullerene limited further improvement of energy conver-
sion efficiency.
2. EXPERIMENTAL DETAILS
2.1. Reagents and Materials
The synthesis of fullerene derivatives and the control
of photovoltaic cell structures have been widely stud-
ied to improve the energy conversion efficiency of pho-
tovoltaic cell. Methanofullerene [6,6]-phenyl C61-butyric
acid methyl ester (PCBM) is the representative fullerene
Fullerene (C60), sarcosine, perylene and poly(2-methoxy-
5-(2-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV)
were purchased from Aldrich Co. Ltd. Poly(3,4-
ethylenedioxythiophene):poly(styrenesulfonate) complex
(PEDOT-PSS) was purchased from Bayer Co. Ltd. Other
chemicals were used as a reagent grade. Synthesis of
∗Author to whom correspondence should be addressed.
4644
J. Nanosci. Nanotechnol. 2011, Vol. 11, No. 5
1533-4880/2011/11/4644/004
doi:10.1166/jnn.2011.3701

So et al.
Fabrication and Characteristics of Fullerene–Perylene Dyad Based Organic Photovoltaic Cell
CHO
CH3
N
Cl2CHOCH3/TiCl4
C60/Sarcosine
1,2-dichlorobenzene,
0 °C, 1 h
Toluene, reflux, heat
Scheme 1. Synthetic route of fullerene–perylene derivative (FP).
fullerene–perylene derivative (FP) was carried out follow-
ing the synthetic routes as shown in Scheme 1.
water and blown by N2 gas. Current–voltage character-
istics were measured using source meters (KEITHLEY-
2400, 237).
2.2. Synthesis of Fullerene–Perylene Derivative (FP)
2.2.1. 3-Fomylperylene
3. RESULTS AND DISCUSSION
Figure 1 showed the UV-Visible absorption spectra
of perylene, fullerene and FP compounds in 1,2-
Dichlorobenzene solution. As shown in Figure 1, the
absorption spectrum of the FP compound is similar to
Perylene (3.9 mmol) in 1,2-dichlorobenzene (100 mL) was
stirred under N atmosphere. 1,1-Dichloromethyl methyl
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2
ether (5.1 mmol) and TiCl (5.9 mmol) were subsequently
University of South Australia
4
added, and the mixture was stirred for 1 h, then allowed
IP : 95.24.27.4
the sum of absorption spectra of two individual com-
to warm to room temperature. The reaction mixture was
poured onto ice (100 g) and concd. HCl (5 mL). The
organic layer was diluted with chloroform (100 mL),
washed with 5% HCl (100 mL), water (300 mL), dried
over Na2SO4 and evaporated. The residue was purified by
column chromatography on silica gel in CHCl3 to give a
desired compound as orange crystal (57 mg, 50.9%).15
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pounds of perylene and fullerene. This result suggests
that there is no ground-state interaction between the two
chromophores, perylene and fullerene. If the charge trans-
fer of ground-state occurs between fullerene and perylene
compounds, charge transfer absorption band appears in
the 450∼650 nm region. The absence of any character-
istic charge transfer band in the absorption spectrum of
FP implies that any charge separation occurs only after
localized excitation on the perylene moiety.16 The redox
behavior of FP was investigated with a CV. The cyclic
voltammograms are shown in Figure 2, and the data are
listed in Table I. We obtained the value of highest occupied
molecular orbital (HOMO) level and lowest unoccupied
molecular orbital (LOMO) level of FP using the cyclic
voltammogram curve. LUMO level of FP was higher than
2.2.2. Fullerene–Perylene Derivative (FP)
A
mixture of C60 (0.3 mmol), 3-formyl perylene
(0.32 mmol) and sarcosine (1.2 mmol) in dried toluene
was refluxed for 24 h under N2 atmosphere. The result-
ing mixture was concentrated and separated on a silica
gel column using toluene/petroleum ether (8:1) to give a
FP (176 mg, 56.7%). Anal. Calc. C: 96.97%, H: 1.67%,
N: 1.36%; Found C: 96.82%, H: 1.83%, N: 1.31%.
2.3. Spectroscopic Measurements
UV-Visible absorption spectrum was performed using
UV/VIS/NIR spectrophotometer (Jasco V-570, Japan). The
redox behavior of FP was studied through the measure-
ment of cyclic voltammetry (CV) (IM6 system, Zahner
Elektrik Co., Germany). The photovoltaic cell configura-
tion used in the present study was ITO/PEDOT-PSS/MEH-
PPV:FP/Al. All layers were fabricated on patterned ITO
(≤15 ꢁ/ꢀ) glass substrate using vacuum evaporation
technique (ULVAC VTR-300M/1ERH evaporator, Japan)
under 10−6 Torr. Before film fabrication, the patterned ITO
substrate was immersed into ultrasonic bath of deionized
water, acetone and methanol for 60 min, subsequently.
Then cleaned ITO glass substrate was rinsed in deionized
Fig. 1. UV-Visible absorption spectra of fullerene, perylene and
fullerene–perylene derivative in 1,2-dichlorobenzene.
J. Nanosci. Nanotechnol. 11, 4644–4647, 2011
4645

Fabrication and Characteristics of Fullerene–Perylene Dyad Based Organic Photovoltaic Cell
So et al.
Fig. 2. Cyclicvoltammogram of fullerene–perylene derivative.
Fig. 3. Current–voltage characteristics for ITO/PEDOT-PSS/MEH-
PPV:C60/Al (solid line), ITO/PEDOT-PSS/MEH-PPV:FP/Al (dash line).
fullerene because of the effect of perylene moiety con-
taining electron donating property. In general, it has been
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found that the addition of the electron donating group to
University of South Australia
17
the fullerene is expected to the increase of LUMO lIePve:l.95.24.27.4
Tue, 18 Sep 2012 11:58:43
Figure 3 showed current–voltage characteristics for the
devices consisting of ITO/PEDOT-PSS/MEH-PPV:C60 or
FP/Al. In the case of MEH-PPV:C60, measured open cir-
cuit voltage (Voc) is 0.57 V, short circuit current density
(Isc) is 2.0 mA/cm2, fill factor is 0.13, and power con-
version efficiency is 0.18%. In the case of MEH-PPV:FP,
Voc and Isc are increased to 0.73 V and 3.25 mA/cm2,
respectively. Fill factor is 0.12 and power conversion
efficiency is 0.30%. Thus, it should be noted that effi-
ciency of photovoltaic cell was improved using fullerene–
perylene derivative which is mainly due to the increase
of LUMO level compared to the LUMO level of C60
and exciton generation according to the introduction of
perylene moiety containing optical activity. In order to
explore the current–voltage characteristics, spin-cast bulk
heterojunction organic photovoltaic cells were fabricated
under various weight ratios of MEH-PPV and FP. Figure 4
showed the result of current–voltage characteristics. Voc
is 0.65∼0.73 V and fill factor is 0.13∼0.16, which are
almost constant independent of FP contents. However, the
Isc was increased with increasing FP content up to 50 wt%
owing to the increase of electron mobility. In the case of
FP over 50 wt%, Isc was decreased, which is caused to
the aggregation of bulky FP molecules.
Fig. 4. Current–voltage characteristics of phohtovoltaic cells consisting
of ITO/PEDOT-PSS/MEH-PPV:FP/Al under various ratios.
4. CONCLUSIONS
A novel fullerene–perylene dyad compound was success-
fully synthesized. And then, organic photovoltaic cell
consisting of ITO/PEDOT-PSS/MEH-PPV:FP/Al was fab-
ricated. Open circuit voltage and short circuit current of
the prepared device using fullerene–perylene dyad was
increased compared to the case of C60, which is mainly due
to the increase of LUMO level and electron carriers. Espe-
cially, it can be concluded that the photovoltaic cell using
FP exhibited high energy conversion efficiency of 0.30%.
Table I. The redox potentials and energy level of fullerene–perylene
derivative.
Acknowledgments: This research was supported by
Basic Science Research Program through the National
Research Foundation of Korea (NRF) funded by
the ministry of Education, Science and Technol-
ogy (20100009816) and Sogang University Foundation
Research Grants in 2008.
E1 (V)
E2 (V)
Energy level (eV)
E1/2ox EHOMO ELUMO Eg
Epc
Epa E1/2ox
Epc
Epa
1.13 1.17 1.15 −0.71 −0.46 −0.59
5.40
3.65
1.74
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So et al.
Fabrication and Characteristics of Fullerene–Perylene Dyad Based Organic Photovoltaic Cell
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Received: 10 June 2009. Accepted: 25 November 2009.
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