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 threedimensional 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.

The short wave near-infrared fluorescence properties of two p-azaquinodimethane (p-AQM)-based conjugated polymers

The absorption,scattering,and autofluorescence of biological tissues in short-wave infrared re-gion(SWIR,900-1700 nm)are relatively low,so SWIR fluorescence usually has deeper pene-tration into living tissues,and can show a higher signal-to-noise ratio when used for imaging in vivo.However,there are few types of organic SWIR fluorescent materials currently.In this work,p-azaquinodimethane(p-AQM)with a quinoid structure is used as the acceptor unit,and car-bazole or fluorene with sp3 hybridization are used as the donor units,two conjugated polymers were synthesized.The quinone structure is conducive to the redshift of absorption and fluores-cence spectra,and the sp3 hybridization structure is conducive to weakening the aggregation quenching of polymer fluorescence.PF and PCz exhibited absorption peaks of 492 nm and 508 nm,respectively.The emission peaks of the two polymers are 920 nm and 950 nm,respec-tively,both in the short-wave near infrared region.The quantum yield(QY)of PF and PCz is 0.4%and 0.3%,respectively.