Polymeric interlayer in CdS-Free electron-selective contact for Sb2Se3 thin-film solar cells

Abstract

High open-circuit voltage in Sb2Se3 thin-film solar cells is a key challenge in the development of earth-abundant photovoltaic devices. CdS selective layers have been used as the standard electron contact in this technology. Long-term scalability issues due to cadmium toxicity and environmental impact are of great concern. In this study, we propose a ZnO-based buffer layer with a polymer-film-modified top interface to replace CdS in Sb2Se3 photovoltaic devices. The branched polyethylenimine layer at the ZnO and transparent electrode interface enhanced the performance of Sb2Se3 solar cells. An important increase in open-circuit voltage from 243 mV to 344 mV and a maximum efficiency of 2.4% was achieved. This study attempts to establish a relation between the use of conjugated polyelectrolyte thin films in chalcogenide photovoltaics and the resulting device improvements.

This research was supported by the Spanish government through grants PID2019-109215RB-C41, PID2019-109215RB-C43, and PID2020-116719RB-C41 funded by MCIN/AEI/10.13039/501100011033. This research was funded by the European Union H2020 Framework Programme under Grant Agreement No. 866018, low-dimensional semiconductors for optically tunable solar harvesters (SENSATE). E.S. acknowledges the ICREA Academia program. One of the authors (T.T.) acknowledges the support of the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya and European Social Fund (2019 FI_B 00456).

Peer Reviewed

Postprint (published version)