High-ĸ dielectric oxide as an interfacial layer with enhanced photo-generation for Gr/Si solar cells

Abstract

In recent years, graphene (Gr) based solar cells have attracted extensive interest because of their ability to produce low cost and highly efficient solar cells. Conventional Gr/Si Schottky junction based solar cells are mostly fabricated by transfer of graphene on silicon substrate. In current work the direct growth of graphene by using the Plasma Enhanced Chemical Vapor Deposition (PECVD) technique was demonstrated to make fabrication more practical on a large scale. Firstly Gr/Si Schottky junction based solar cells were fabricated, and by optimizing the growth process, power conversion efficiency (PCE) of about 3.5% was achieved. Additionally, we demonstrated a metal insulator semiconductor (MIS) structure by introducing hafnium oxide (HfO2), and an enriched efficiency of 6.68% was reached. Furthermore, the chemical doping of Gr grown on top of HfO2 passivated Si was done and the efficiency was further enhanced by 8.5%. This study also suggests that the Voc of the Gr/HfO2/Si solar cells strongly depends on the thickness of the HfO2 interfacial layer. These solar cells proved reliable as their efficiency was still consistent even after four months. The current study envisions the use of graphene based solar cells for commercial application.