Molecular contacts with an orthogonal π-skeleton induce amorphization to enhance perovskite solar cell performance

Abstract

Perovskite solar cells represent a promising class of photovoltaics that have achieved exceptional levels of performance within a short time. Such high efficiencies often depend on the use of molecule-based selective contacts that form highly ordered molecular assemblies. Although this high degree of ordering usually benefits charge-carrier transport, it is disrupted by structure deformation and phase transformation when subjected to external stresses, which limits the long-term operational stability of perovskite solar cells. Here we demonstrate a molecular contact with an orthogonal π-skeleton that shows better resilience to external stimuli than commonly used conjugated cores. This molecular design yields a disordered, amorphous structure that is not only highly stable but also demonstrates exceptional charge selectivity and transport capability. The perovskite solar cells fabricated with this orthogonal π-skeleton molecule exhibited enhanced long-term durability in accelerated-ageing tests. This orthogonal π-skeleton functionality opens new opportunities in molecular design for applications in organic electronics. Perovskite solar cells often rely on ordered molecular contacts for favourable charge-carrier transport, and any organizational disruption reduces device efficiency. Now a contact featuring an orthogonal π-skeleton has been shown to afford a high resilience to external stimuli plus long-term durability in accelerated-ageing tests.