Crystal defects mitigating agents for high power conversion efficiency and stability of perovskite photovoltaic devices

This invention relates to an optoelectronic and/or photovoltaic device comprising acompound used as crystal defect mitigating agent or passivating agent, said compound beingselected from a compound of formula (I),a compound of formula (II),a mixture thereof, or a compound of formula (III) being selected from anyone of formulae(III.1), (III.2). (III.3), (IlI4) and (III.5) below.