Programmable Charge Trap for Junction-less selective extraction of holes in Solar Cells

Abstract

Selective extraction of photo-generated carriers is a fundamental challenge in solar cells which is usually achieved through junctions with the associated doping as well as band offset differences. In this context, here we propose a new paradigm for selective extraction for majority carriers through novel usage of the programmable charge trap which comprises of Oxide-Nitride-Oxide (ONO) stack and has the primary function of holding electrically injected charge. Through detailed numerical simulations, here we show that such a charge trap with an additional metal contact can (i) compensate for efficiency loss due to sub-optimal passivation and sub-optimal hole selectivity in homojunction as well as transition metal oxide-based heterojunction solar cells and (ii) can also function as a standalone hole selection scheme. The proposed scheme, with its easy integration and the capability of programmable compensation of performance loss, is of interest to the photovoltaic community.