Electronic Supplementary Material (ESI) for Energy & Environmental Science. This journal is The Royal Society of Chemistry 2014 Supporting Information Perylene Diimides: a Thickness-Insensitive Cathode Interlayer for High Performance Polymer Solar Cells Zhi-Guo Zhang, Boyuan Qi, Zhiwen Jin, Dan Chi, Zhe Qi, Yongfang Li* and Jizheng Wang* Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China) E-mail: jizheng@iccas.ac.cn (J. Wang) and liyf@iccas.ac.cn (Y. Li) Figure S1. Equivalent circuit of the solar cell. The current density-voltage characteristic of an organic photovoltaic device can be described with conventional (Si) p-n solar cells, so the following simplified expression can be derived for the open-circuit voltage V OC : (1) where J SC is the short-circuit current density under illumination, J 0 is the reverse bias saturation current density, q is the elementary charge, K is Boltzmann s constant, T is temperature (T is 300 K here.), KT is thermal energy, and n is the ideality factor of 1
the diode, in which n is a key factor to reflect whether the semiconductor device is good or not. Current (A) 10-6 10-8 10-10 10-12 PDIN 7.6*10-5 S.cm -1 PDINO 8.1*10-6 S.cm -1 PFN 6.8*10-9 S.cm -1 0 10 20 30 40 50 Voltage (V) Figure S2. The measurements of the conductivities. Figure S3. J-V curves of the PSCs based on PTB7/PC 70 BM with PFN cathode interlayer under the illumination of AM1.5G, 100 mw/cm 2. 2
Current Density (macm -2 ) 5 0-5 -10-15 PDINO/Ag PDIN/Ag PDIN/Au PDINO/Au 0.0 0.5 1.0 Voltage (V) Figure S4. J-V curves of the PSCs based on PTB7/PC 70 BM with PDIN (14 nm) or PDINO (10 nm) cathode interlayer and different metal top electrodes under the illumination of AM1.5G, 100 mw/cm 2. Figure S5. The IPCE spectra of the PSCs based on PTB7/PC 70 BM with PDINO cathode interlayerwith different interlayer thickness along with that of the device with Ca/Al cathode. 3
3000 2500 2000 PDIN PDINO Counts 1500 1000 500 0 5 10 15 20 25 30 2-theta Figure S6. X-ray diffraction patterns of the polymer films drop-cast onto a silicon substrate. Absorbance(a. u.) 1.0 0.8 0.6 0.4 0.2 PDIN PDINO 0.0 450 500 550 600 650 700 750 800 850 Wavelength (nm) Figure S7. PL spectrum of PDINO/PDIN in the solid state. 4
Figure S8. Normalized PCEs under ambient condition for based devices. PTB7/PC 70 BM 100 Reflectance(a. u.) 80 60 40 20 0 PDINO/Al Cal/Al 300 400 500 600 700 800 Wavelength (nm) Figure S9. The reflectance spectra of the conventional Ca/Al and the PDINO/Al PTB7-Th: PC 70 BM PSCs. 5
Current Density (macm -2 ) 2.0 1.5 1.0 0.5 0.0-0.5-1.0-1.5-2.0-0.6-0.4-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Voltage (V) PTB7/PDINO Figure S10. J-V curves of the PSCs based on PTB7/PDINO bilayer device with Al as cathode under the illumination of AM1.5G, 100 mw/cm 2. 6
Table S1.The Optimized geometry and the dipole moments obtained from DFT calculations on PDINO, PDIN, trimenthylamine and trimethylamine oxide at B3LYP/6-31G* level.[1] Chemical Name Optimized geometry Dipole moment PDIN 1.0757 PDINO 7.2693 Trimethylamine 0.5806 Trimethylamine Oxide 4.3739 For the two PDIs, they bear the same alkyl chains at the both side. Due to lower energy difference of the alkyl chain orientations, they are stochastic distribution in the solid films. So their symmetric orientation in solid film for a given molecule can t be guaranteed. Thus, dipole moment could be generated in case of an asymmetric orientation. Reference [1]. Gaussian 03, Revision E.01, M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, J. A. Montgomery, Jr., T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, P. Y. Ayala, K. Morokuma, G. A. Voth, P. Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dapprich, A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q. Cui, A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L. Martin, D. J. Fox, T. Keith, M. A. Al- Laham, C. Y. Peng, A. Nanayakkara, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M. W. Wong, C. Gonzalez, and J. A. Pople, Gaussian, Inc., Wallingford CT, 2004. 7