A Highly Conductive Titanium Oxynitride Electron-Selective Contact for Efficient Photovoltaic Devices

Abstract

High-quality carrier-selective contacts with suitable electronic properties are a prerequisite for photovoltaic devices with high power conversion efficiency (PCE). In this work, an efficient electron-selective contact, titanium oxynitride (TiO_x N_y ), is developed for crystalline silicon (c-Si) and organic photovoltaic devices. Atomic-layer-deposited TiO_x N_y is demonstrated to be highly conductive with a proper work function (4.3 eV) and a wide bandgap (3.4 eV). Thin TiO_x N_y films simultaneously provide a moderate surface passivation and enable a low contact resistivity on c-Si surfaces. By implementation of an optimal TiO_x N_y -based contact, a state-of-the-art PCE of 22.3% is achieved for a c-Si solar cell featuring a full-area dopant-free electron-selective contact. Simultaneously, conductive TiO_x N_y is proven to be an efficient electron-transport layer for organic photovoltaic (OPV) devices. A remarkably high PCE of 17.02% is achieved for an OPV device with an electron-transport TiO_x N_y layer, which is superior to conventional ZnO-based devices with a PCE of 16.10%. Atomic-layer-deposited TiO_x N_y ETL on a large area with a high uniformity may help accelerate the commercialization of emerging solar technologies.

Keywords: electron-selective contacts; organic solar cells; passivating contacts; silicon solar cells; titanium oxynitride.