S. Shen et al. / Organic Electronics 14 (2013) 875–881
881
stability, strong absorption, deep HOMO energy level and
relatively higher hole mobility. The PCE of the bulk hetero-
junction OSC based on a blend of S(TPA-bTV-CA) and PC70-
-28
-30
-32
2
BM (1:3, w/w) reached 2.1% with a Jsc of 4.64 mA/cm , a Voc
of 0.91 V and a FF of 50%, under the illumination of AM.1.5,
2
2
)
100 mW/cm .
b
i
-34
36
-38
40
-V
References
-
apl
V
(
/
[1] Y.F. Li, Acc. Chem. Res. 45 (2012) 723–733.
3
[
[
[
2] S. Roquet, A. Cravino, P. Leriche, O. Aleveque, P. Frere, J. Roncali, J.
Am. Chem. Soc. 128 (2006) 3459–3466.
3] S. Karpe, A. Cravino, P. Frere, M. Allain, G. Mabon, J. Roncali, Adv.
Funct. Mater. 17 (2007) 1163–1171.
JL
-
0
300
600
900
1200
1500
4] J. Roncali, P. Leriche, A. Cravino, Adv. Mater. 19 (2007) 2045–2060.
(
(Vappl -Vbi /)L)0.5 (V/cm)0.5
[5] D. Demeter, T. Rousseau, P. Leriche, T. Cauchy, R. Po, J. Roncali, Adv.
Funct. Mater. 21 (2011) 4379–4387.
[6] E. Ripaud, T. Rousseau, P. Leriche, J. Roncali, Adv. Energy Mater. 1
Fig. 7. Plot of ln(JL /V ) versus (V/L)0.5of the device ITO/PEDOT:PSS/
S(TPA-bTV-CA)/Au for the measurement of hole mobility.
3
2
(
2011) 540–545.
[
[
7] C.-Q. Ma, E. Mena-Osteritz, T. Debaerdemaeker, M.M. Wienk, R.N.J.
Janssen, P. Bauerle, Angew. Chem. Int. Ed. 46 (2007) 1679–1683.
8] C.-Q. Ma, M. Fonrodona, M.C. Schikora, M.M. Wienk, R.A.J. Janssen, P.
Bauerle, Adv. Funct. Mater. 18 (2008) 3323–3331.
which indicates that the visible absorption of S(TPA-bTV-
[9] Y.S. Liu, X.J. Wan, B. Yin, J.Y. Zhou, G.K. Long, S.G. Yin, Y.S. Chen, J.
Mater. Chem. 20 (2010) 2464–2468.
10] X. Sun, Y. Zhou, W. Wu, Y. Liu, W. Tian, G. Yu, W. Qiu, S. Chen, D. Zhu,
J. Phys. Chem. B 110 (2006) 7702–7707.
CA) did make
conversion.
a contribution to the photovoltaic
[
[
[
11] L.L. Xue, J.T. He, X. Gu, Z.F. Yang, B. Xu, W.J. Tian, J. Phys. Chem. C 113
(
2009) 2911–12917.
12] A.B. Tamayo, B. Walker, T.Q. Nguyen, J. Phys. Chem. C 112 (2008)
1545–11551.
3.5. AFM morphology and hole mobility
1
Morphology of the photoactive layer plays a critical role
[13] C. He, Q.G. He, Y.P. Yi, G.L. Wu, F.L. Bai, Z.G. Shuai, Y.F. Li, J. Mater.
Chem. 18 (2008) 4085–4090.
in order to achieve good performance of OSCs. According to
the literature [32], nanoscale phase separation enables a
large interface area for exciton dissociation and a path
for electron transport. The morphology of the S(TPA-bTV-
CA):PC70BM (1:3, w/w) blend film was investigated by
atomic force microscopy (AFM). Fig. 6 shows the AFM
height and phase images of S(TPA-bTV-CA):PC70BM (1:3,
w/w) blend film. The root-mean-square (rms) roughness
of the film was 11.8 nm from the height image (see
Fig. 6a). And the phase image in Fig. 6b shows visible phase
separation with an elongated and ordered network of do-
nor/acceptor domains, but the domain sizes are too big
[
14] J. Zhang, Y. Yang, C. He, Y.J. He, G.J. Zhao, Y.F. Li, Macromolecules 42
2009) 7619–7622.
(
[15] D. Deng, Y. Yang, J. Zhang, C. He, M.J. Zhang, Z.G. Zhang, Z.J. Zhang,
Y.F. Li, Org. Electron. 12 (2011) 614–622.
[
16] D. Deng, S.L. Shen, J. Zhang, C. He, Z.J. Zhang, Y.F. Li, Org. Electron. 13
2012) 2546–2552.
(
[
17] (a) J. Zhang, D. Den, C. He, M.J. Zhang, Z.G. Zhang, Z.J. Zhang, Y.F. Li,
Chem. Mater. 23 (2010) 817–822;
(
2
b) P. Arsenyan, E. Paegle, S. Belyakov, Tetrahedron Lett. 51 (2010)
05–208.
[
18] (a) P.F. Xia, X.J. Feng, J.P. Lu, S.W. Tsang, R. Movileanu, Y. Tao, M.S.
Wong, Adv. Mater. 20 (2008) 4810–4815;
(
(
b) M.C. Cui, Z.J. Li, R.K. Tang, H.M. Jia, B.L. Liu, Eur. J. Med. Chem. 46
2011) 2908–2916.
[
[
[
[
[
19] Y.M. Sun, G.C. Welch, W.L. Leong, C.J. Takacs, G.C. Bazan, A.J. Heeger,
Nature Mater. 11 (2012) 44–48.
20] G. Yu, J. Gao, J. Hummelen, F. Wudl, A.J. Heeger, Science 270 (1995)
(
larger than 100 nm). The relatively lower IPCE values
and lower short circuit current density could be due to
the big domain sizes.
Hole mobility of the molecule was measured by space-
charge-limited-current (SCLC) method [33] with the device
structure of ITO/PEDOT:PSS/S(TPA-bTV-CA) film/Au
1789–1791.
21] Y. Lin, Z.-G. Zhang, H. Bai, Y. Li, X. Zhan, Chem. Commun. 48 (2012)
9655–9657.
22] Y. Lin, P. Cheng, Y. Li, X. Zhan, Chem. Commun. 48 (2012) 4773–
4775.
23] Y. Liu, X. Wan, F. Wang, J. Zhou, G. Long, J. Tian, J. You, Y. Yang, Y.
Chen, Adv. Energy Mater. 1 (2011) 771–775.
(
9
Fig. 7), and the thickness of S(TPA-bTV-CA) film is
4 nm. Fig. 7 shows the plot of ln(JL /V ) versus (V/L) of
3
2
0.5
[24] J. Zhou, X. Wan, Y. Liu, Y. Zuo, Z. Li, G. He, G. Long, W. Ni, C. Li, X. Su,
Y. Chen, J. Am. Chem. Soc. 134 (2012) 16345–16351.
[
the device, and the hole mobility of S(TPA-bTV-CA) calcu-
25] Z.C. He, C.M. Zhong, S.J. Su, M. Xu, H.B. Wu, Y. Cao, 10.1038/
nphoton.2012.190.
ꢀ
4
2
ꢀ1 ꢀ1
lated from the results is 2.03 ꢁ 10 cm V
s , indicat-
ing that S(TPA-bTV-CA) possesses a relatively higher hole
mobility in comparison with other TPA-based molecules.
[26] Q.J. Sun, H.Q. Wang, C.H. Yang, Y.F. Li, J. Mater. Chem. 13 (2003) 800.
[
[
[
27] Y.J. He, G.J. Zhao, B. Peng, Y.F. Li, Adv. Funct. Mater. 20 (2010) 3383–
389.
3
28] M.M. Wienk, J.M. Kroon, W.J.H. Verhees, J. Knol, J.C. Hummelen, P.A.
van Hal, R.A.J. Janssen, Angew. Chem. Int. Ed. 42 (2003) 3371.
29] F.B. Kooistra, V.D. Mihailetchi, L.M. Popescu, D. Kronholm, P.W.M.
Blom, J.C. Hummelen, Chem. Mater. 18 (2006) 3068.
4
. Conclusions
A new star-shaped D–
p
–A molecule S(TPA-bTV-CA)
[30] B.C. Thompson, J.M.J. Frechet, Angew. Chem. Int. Ed. 47 (2008) 58.
[31] Wenseleers, F. Stellacci, T. Meyer-Friedrichsen, T. Mangel, C.A.
Bauer, S.J.K. Pond, S.R. Marder, J.W. Perry, J. Phys. Chem. B. 106
with triphenylamine (TPA) as core and donor unit, CA as
0
end group and acceptor unit, and 2,2 -bithiophene-vinyl-
(
2002) 6853.
ene (bTV) as
p
ꢀbridge, was designed and synthesized for
[
[
32] G. Li, V. Shrotriya, J.S. Huang, Y. Yao, T. Moriarty, K. Emery, Y. Yang,
Nature Mater. 4 (2005) 864–868.
33] Q. Zheng, B.J. Jung, J. Sun, H.E. Katz, J. Am. Chem. Soc. 132 (2010)
the application as donor material in solution-processed
bulk-heterojunction organic solar cells (OSCs). S(TPA-
bTV-CA) shows good solution processability and thermal
5394–5404.