Achieving a Record Open‐Circuit Voltage for Organic/Si Hybrid Solar Cells by Improving Junction Quality

Abstract

Nanostructured Si has attracted widespread attention due to its strong light‐harvesting ability, which is beneficial to improve the performance of solar cells. However, the poor contact of the organic/nanostructured Si interface and the large number of recombination centers on the Si surface result in an unsatisfactory open circuit voltage (VOC) and fill factor (FF) of the device. Herein, a simple and versatile method, Si nanowires modified with tetramethylammonium hydroxide (TMAH) and poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) doped with 3‐glycidoxypropyltrimethoxydsilane (GOPS), is proposed to improve the contact quality of the heterojunction. TMAH treatment adjusts the morphology of the Si nanowires and makes the surface smoother, effectively inhibiting surface recombination at the heterojunction interface. Moreover, the GOPS‐doped PEDOT:PSS solution can achieve conformal contact on the surface of nanostructured Si, which is more conducive to the extraction and separation of charges. As a result, a record VOC of 660 mV is obtained for PEDOT:PSS/nanostructured Si hybrid solar cells. In addition, the short circuit current density (JSC) is as high as 33.00 mA cm−2, and the FF is as high as 69.03%; therefore, the efficiency of the device reaches 15.01%. The results provide a simple and feasible strategy to improve the junction quality and performance of organic/Si solar cells.