Simple Approach of Fabricating High Efficiency Si Nanowire/Conductive Polymer Hybrid Solar Cells

We present a simple approach of fabricating high-efficiency hybrid solar cells based on silicon nanowires (SiNWs) and a conductive polymer, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). PEDOT:PSS is directly spin coated on vertical SiNW arrays fabricated by electroless chemical etching to form a core-sheath heterojunction. A silver grid is used as the top anode. Compared to a planar Si/PEDOT:PSS cell, the power conversion efficiency of a 1-cm² SiNW/PEDOT:PSS cell increases greatly from 6.2% to 9%. Cells with different SiNW lengths are also studied, and it is found that enhanced aggregation of longer SiNWs leads to poor surface coverage by PEDOT and, hence, degraded solar cell characteristics.