Organic/silicon nanowires (SiNWs) hybrid solar cells have recently been recognized as one of potentially low-cost candidates for photovoltaic application. Here, we have controllably prepared a series of uniform silicon nanowires (SiNWs) with various diameters on silicon substrate by metal-assisted chemical etching followed by thermal oxidization, and then fabricated the organic/SiNWs hybrid solar cells with poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). It is found that the reflective index of SiNWs layer for sunlight depends on the filling ratio of SiNWs. Compared to the SiNWs with the lowest reflectivity (LR-SiNWs), the solar cell based on the SiNWs with low filling ratio (LF-SiNWs) has a higher open-circuit voltage and fill factor. The capacitance-voltage measurements have clarified that the built-in potential barrier at the LF-SiNWs/PEDOT:PSS interface is much larger than that at the LR-SiNWs/PEDOT one, which yields a strong inversion layer generating near the silicon surface. The formation of inversion layer can effectively suppress the carrier recombination, reducing the leakage current of solar cell, and meanwhile transfer the LF-SiNWs/PEDOT:PSS device into a p-n junction. As a result, a highest efficiency of 13.11% is achieved for the LF-SiNWs/PEDOT:PSS solar cell. These results pave a way to the fabrication of high efficiency organic/SiNWs hybrid solar cells.
Graphene/silicon (Gr/Si) solar cells have triggered considerable interest for their potential in low‐cost and high‐efficiency photovoltaic applications. However, the performance of Gr/Si solar cells is still limited by poor Gr conductivity and carrier recombination at the interface. In this study, a solution‐processable poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) thin film is employed as a carrier selective interlayer in the graphene and n‐type Si solar cells, which can increase the work function and conductivity of the Gr due to photoinduced p‐type doping under light illumination. Consequently, the Schottky barrier height of the solar cells is enhanced, whereas the carrier recombination at the interface is suppressed. The utilization of antireflection and additional chemical doping at the other side of the Gr layer further improves the performance of the solar cells, which shows a power conversion efficiency of 12.95% with high stability. This study paves a new venue for the development of Gr/Si solar cells toward real applications.
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