In Situ MAPbI₃ Perovskite Nanostructures Formed by a Poly[(phenylglycidyl ether)-co-formaldehyde] Epoxide for Enhanced Stability and Photoluminescence

Metal halide perovskites (MHPs) have emerged as promisingnext-generationoptoelectronic materials and achieved remarkable performances in bothlight-emitting diodes (LEDs) and solar cells (SCs). Despite reachingmarket demands such as high efficiencies and low manufacturing cost,the long-term stability of MHPs is still a massive challenge for commercialization.The presence of surface and bulk defects due to low-temperature solution-processablemethods causes past degradation of perovskites. Here, we have investigatedthe passivation strategy for methylammonium lead iodide (MAPbI(3)) using resin polymer poly[(phenylglycidyl ether)-co-formaldehyde] (PCF). PCF acts as a Lewis base additivewith an electron-donating oxygen atom, which can coordinate with undercoordinatedPb(2+) ions or NH3 (+) in perovskite crystals,developing smaller nanocrystalline grains with reduced defects. Asa result, the PCF-passivated samples exhibit improved stability againstmoisture in a humid ambient environment (RH > 70%). Moreover, enhancedphotoluminescence (PL) and lifetime were achieved without encapsulation.Furthermore, LEDs are demonstrated using the optimized PCF content.These results show the importance of resin polymers, which performsmultiple functionalities such as nanocrystalline grain formation,defect passivation, and stability improvements for optoelectronicdevices.