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The study of silicon nanostructure, such as silicon nanowires (SiNRs) or silicon micropyramids (SiMPs) for solar cell applications is attractive due to excellent light harvesting and good anti-refractive capability. Nowadays, inorganic-organic hybrid solar cell is widely investigated such as GaAs NRs hybrid P3HT,CdTe NRs hybrid P3OT, and TiO2 NRs hybrid P3HT. In this paper, we create a hierarchical structure consisting of SiNRs and SiMPs and hybrid the hole conducting polymer poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The schematic of the fabricated structure is shown in Figure 2.
Hierarchical structures consisting of micropyramids and nanowires are demonstrated in Si/PEDOT:PSS hybrid solar cells to achieve a power conversion efficiency up to 11.50% with excellent omnidirectionality. The structure provides a combined concepts of superior light trapping ability, significant increase of p-n junction areas, and short carrier diffusion distance, improving the photovoltaic characteristics including JSC, FF, and PCE.
The structure provides a combined concepts of superior light trapping ability, significant increase of p-n junction areas, and short carrier diffusion distance, improving the photovoltaic characteristics including JSC, FF, and PCE. The enhancement of power generation is up to 253.8% at high incident angles, showing the outstanding omnidirectional operation ability of hybrid cells with hierarchical Si surfaces. This properly designed hierarchical-structured device paves a promising way for developing low cost, high efficiency, and practical solar applications in the future.
Figure 3. Schematic illustration of the fabrication process for a hierarchical /polymer solar cell.
(a) pyramid Si
(b) after SiNWs by metal assisted etching,
(c) after a spin-coating of PEDOT:PSS, with a thickness of 30 nm and
(d) after deposition of a top electrode, Ag, with a thickness of 500 nm.
Figure 2. SEM images of MP-textured Si substrates (a) without NWs, with (b) 30 nm, (c) 185 nm, (d) 234 nm, (e) 357 nm, and (f) 602 nm NWs, respectively.
Fabrication and Characterization of PV Devices
Above-11%-Efficiency Organic–Inorganic Hybrid Solar Cells with Omnidirectional Harvesting Characteristics by Employing Hierarchical Photon Trapping StructuresWan-Rou Wei,1,2 Meng-LinTsai,1 Shih-ShiangTai ,1Cherng-Rong Ho,1 Shin-Hung Tsai,1Ren-Jei Chung,2* and Jr-Hau He1*1 Institute of Photonics and Optoelectronics & Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan , R.O.C. *Email: [email protected] Graduate Institute of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, Taiwan, R.O.C. *Email: [email protected]
Figure 1. Device structure
Figure 7. IPCE spectra of flat Si cell, pyramid Si and
pyramid Si with 234 nm SiNWs.
Figure 6. Current density-voltage (J-V) characteristics of planar, micropyramid and hierarchical structured Si with various Si NW lengths with and without hot DI water treatments.
Figure 4. (a) Total reﬂectance spectra of flat Si, pyramid Si with various lengths of 0, 30, 185 and 234 nm SiNWs coated with PEDOT:PSS. Specular reﬂectance spectra of (b) flat Si, pyramid Si with (c) 0 and (d) 234 nm SiNWs coated with PEDOT:PSS.
Figure 9. (a) Schematic of incident angle-dependent power
generated over a day. (b) Incident angle dependence of
generated maximum power (c) enhancement of generated
maximum power, and (d) estimated average daily power
density generated from the devices.
Figure 8. NW length-dependent photovoltaic characteristic trends ((a) Voc, (b) Jsc, (c) FF and (d) PCE) of hierarchical-structured Si devices.
Figure 5. Simulated optical field using FDTD (a) flat Si (b) pyramid Si (C) pyramid Si with 234 nm SiNWs coated with PEDOT:PSS (d) Optical absorption detected at the interface between PEDOT:PSS and Si at 550 nm.