Enhancing the Efficiency of Silicon-Based Solar Cells by the Piezo-Phototronic Effect Laian Zhu,, Longfei Wang,, Caofeng Pan, Libo Chen, Fei Xue, Baodong Chen, Leijing Yang, Li Su, and Zhong Lin Wang*,, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, National Center for Nanoscience and Technology (NCNST), Beijing 100083, China School of Material Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States These authors contributed equally to this work. * E-mail: zhong.wang@mse.gatech.edu This word file includes: Figure S1:Picture of the samles ackaged into PDMS. Figure S2:SEM images of the designed atterns. Figure S3:Performance of the solar cell with attern P1. Sulementary Note 1: Performance of the Solar Cell with Pattern P1. Figure S4:Concentration of P + as a function of imlanting deth for heavy-doed n + -Si and light-doed n-si. Sulementary Note 2: A Brief Introduction of Ion Imlantation. References
Figure S1. Picture of the samles ackaged into PDMS.
Figure S2. SEM images of the designed atterns (a) P2, (b) P3, and (c) P4.
Figure S3. Performance of the solar cell with attern P1. a) J-V characteristics of the silicon-based nanoheterostructure solar cell with attern P1 under different illumination. The inset denotes J-V characteristics of P1 in the dark. b) The illumination intensity deendence of the short-circuit current density (J SC ) and the oen-circuit voltage (V OC ). c) The illumination intensity deendence of the solar energy conversion efficiency (η) and the fill factor (FF). Sulementary Note 1: Performance of the Solar Cell with Pattern P1 Figure S3a demonstrates an enhanced J-V characteristics of the solar cell with the increase of illumination intensities, ranging from 20 to 100 mw/cm 2. The deendency of the erformance arameters on the illumination intensity is shown in Figure S3b, c. Secifically, an efficiency (η) of 8.3% is obtained with an oen-circuit voltage V OC
0.603 V, short-circuit current density J SC 27.85 ma/cm 2 and fill factor FF 0.5 under AM 1.5G illumination. The short-circuit current density can be exressed as J eq( L L ), SC n where e is an elementary charge, and Q is an average generation rate of hoto-excited carriers within the diffusion length ( L L ) in the -n junction. 1 As n shown from Figure S3b, J SC exhibits a near-linear deendency on the intensity, which is due to that the hotocurrent in this regime is roortional to the hoton flux or the carrier generation rate with a constant minority carrier lifetime. The oen-circuit voltage can be exressed as V 1 k T 0 SC OC E ln( ), er e I00 I where E is the energy band difference between the conduction band of a n-tye inorganic material and the conduction band of a -tye inorganic material, r is the ideality factor, I 00 is the refactor of the reverse saturation current. 2,3 As shown from Figure S3c, V OC increases from 0.582 to 0.603 V with the increase of intensity, which is attributed to the thermal heating effect as well as the enhanced short-circuit current of the device. 1,4 The fill factor FF almost remains unchanged with illumination intensity. As the solar energy conversion efficiency can be exressed as V J FF/, P OC the calculated is enhanced from 6.8% to 9% with the illumination intensity increasing from 20 to 100 mw/cm 2. SC
Figure S4. Concentration of P + as a function of imlanting deth for heavy-doed n + -Si and light-doed n-si. Sulementary Note 2: A Brief Introduction of Ion Imlantation For ion imlantation in amorhous or monocrystal substances, if the imlanted energy ( E ) and dose (the number of imlanted ions er unit area, N s ) of the target element are known, one can get the distribution of the density of the imlanted ions by a Gaussian function: 5-10 x R N x N 2 R 2 ( ) max ex, 2 where x, N, R, and max R are the location of ion imlantation, the maximum of the density of imlanted ions, the mean rojected range, and the standard deviation of the mean rojected range, resectively. The maximum of the density of imlanted ion can be exressed as
N N s max, 2 R and R and R can be obtained from references according to the given energy E. 8-10 For this heavy-doed n + -Si solar cell with imlanted energy of 80 KeV and dose of 10 15 cm -2, one can get R 97.4 nm and R 36.7 nm. And for the light-doed n-si solar cell with imlanted energy of 40 KeV and dose of 1.5 10 11 cm -2, one can get R 48.8 nm and R 20.1nm. The distribution of the density of the imlanted hoshorus ions for the two cases is shown in Sulementary Figure S4. References (1) Sze, S. M.; Ng, K. K. Physics of Semiconductor Devices. John Wiley & Sons: Hoboken, NJ, 2006. (2) Yang, Y.; Guo, W.; Zhang, Y.; Ding, Y.; Wang, X.; Wang, Z. L. Piezotronic Effect on the Outut Voltage of P3HT/ZnO Micro/Nanowire Heterojunction Solar Cells. Nano Lett. 2011, 11, 4812-4817. (3) Zhu, L.; Wang, L.; Xue, F.; Chen, L.; Fu, J.; Feng, X.; Li, T.; Wang, Z. L. Piezo-Phototronic Effect Enhanced Flexible Solar Cells Based on n-zno/-sns Core Shell Nanowire Array. Adv. Sci. 2016, 1600185. (4) Fan, Z.; Razavi, H.; Do, J.-W.; Moriwaki, A.; Ergen, O.; Chueh, Y.-L.; Leu, P. W.; Ho, J. C.; Takahashi, T.; Reichertz, L. A.; Neale, S.; Yu, K.; Wu, M.; Ager, J. W.; Javey, A. Three-Dimensional Nanoillar-Array Photovoltaics on Low-Cost and Flexible Substrates. Nat. Mater. 2009, 8, 648-653. (5) Lindhard, J.; Scharff, M.; Schioett, H. E. Range Concets and Heavy Ion Ranges. Munksgaard: 1963. (6) Townsend, P. D.; Chandler, P. J.; Zhang, L. Otical Effects of Ion Imlantation. Cambridge University Press: Cambridge, 2006. (7) Ziegler, J. F. Ion Imlantation: Science and Technology. Ion Imlantation Technology Co.: New York, 1996. (8) Luo, J. Ion Imlantation Physics. Shanghai Science and Technology Press: Shanghai, 1984. (9) Anders, A. Handbook of Plasma Immersion Ion Imlantation and Deosition. John Wiley & Sons, Inc.: New York, 2000. (10) Shao, J.; Round, M.; Qin, S.; Chan, C. Dose Time Relation in BF3 Plasma Immersion Ion Imlantation. J. Vac. Sci. Technol. A 1995, 13, 332-334.