Spatial configuration engineering of perylenediimide-based non-fullerene electron transport materials for efficient inverted perovskite solar cells

Due to their excellent photoelectron chemical properties and suitable energy level alignment with perovskite, perylene diimide (PDI) derivatives are competitive non-fullerene electron transport material (ETM) candidates for perovskite solar cells (PSCs). However, the conjugated rigid plane structure of PDI units result in PDI-based ETMs tending to form large aggregates, limiting their application and photovoltaic performance. In this study, to restrict aggregation and further enhance the photovoltaic performance of PDI-type ETMs, two PDI-based ETMs, termed PDO-PDI2 (dimer) and PDO-PDI3 (trimer), were constructed by introducing a phenothiazine 5,5-dioxide (PDO) core building block. The research manifests that the optoelectronic properties and film formation property of PDO-PDI2 and PDO-PDI3 were deeply affected by the molecular spatial configuration. Applied in PSCs, PDO-PDI3 with three-dimensional spiral molecular structure, exhibits superior electron extraction and transport properties, further achieving the best PCE of 18.72% and maintaining 93% of its initial efficiency after a 720-h aging test under ambient conditions.