Affiliation:
1. Department of Chemistry Biology and Biotechnology University of Perugia Via Elce di Sotto 8 Perugia 06123 Italy
2. Computational Laboratory for Hybrid/Organic Photovoltaics (CLHYO) Istituto CNR di Scienze e Tecnologie Chimiche (SCITEC‐CNR) Via Elce di Sotto 8 Perugia 06123 Italy
3. Department of Natural Sciences & Mathematics College of Sciences & Human Studies Prince Mohammad Bin Fahd University Dhahran 34754 Saudi Arabia
4. SKKU Institute of Energy Science and Technology (SIEST) Sungkyunkwan University Suwon 440‐746 South Korea
Abstract
AbstractTin‐halide perovskites (THP) are emerging materials for photovoltaics with optoelectronic properties potentially rivaling lead‐based analoges. Their efficiencies in solar cells are, however, severely limited by the high sensitivity of tin to oxygen and the heavy p‐doping natively present in the material. While the effects of oxygen can be mitigated by using reducing agents upon the synthesis and by encapsulating the device, the native p‐doping caused by the high density of acceptor defects remains a challenge to be further addressed for prolonging carrier lifetimes and, consequently, device efficiency. In this work, potential compositional engineering strategies aimed at reducing the p‐doping of this class of materials and increasing their efficiency in solar cells are investigated. Based on density functional theory simulations it is demonstrated that THP doping with d1s2 trivalent ions effectively decreases the hole background density and the density of the deep defects responsible for the non‐radiative recombination in these materials. This effect is enhanced by alloying iodide with small fractions of bromide, up to 33%. Higher bromide fractions, instead, are detrimental due to the increased non‐radiative recombination. These results may provide useful guidelines to experimentalists for improving the optoelectronic quality of THPs and consequently of the ensuing devices.