Stabilized the Purified CsPbI ₃ Quantum Dots With Extended Processing Windows for LED Fabrication

ABSTRACT The elimination of redundant surface organic ligands on perovskite quantum dots (PQDs) is a critical procedure for the construction of high‐efficiency light‐emitting diodes (LEDs). Nevertheless, such ligand removal readily induces undesirable phase transition owing to the intrinsically unstable surface configuration of PQDs, which severely hinders the large‐scale manufacturing of high‐performance LEDs. Herein, we develop tetrabutylammonium hexafluorophosphate (TBAPF 6 ) surface reconstruction of CsPbI 3 PQDs during di‐isooctylphosphinic acid (DSPA) assisted synthesis and purification. The short chain DSPA has strong coordination with PQDs, while TBA + ions are compensated for Cs + surface vacancies, and PF 6 − ions combine onto Pb 2+ sites to stabilize the structure through filling I − vacancies. This strategy substantially suppressed phase transformation during synthesis and purification, thereby enhancing the moisture and oxygen stability of the PQDs to extend the processing window of device fabrication. LEDs fabricated using freshly stored PQD within 7 days showed negligible efficiency degradation, yielding a peak external quantum efficiency (EQE) over 25%. Notably, even after long‐term storage for 30 days, the assembled LEDs still achieved a high EQE of more than 22%. Accordingly, this strategy provides a viable pathway for the scalable preparation of wide‐processing‐window LEDs.