To fine-tune surface ligands towards high-performance devices,wedeveloped an in situ passivation process for all-inorganic cesium lead iodide (CsPbI 3)perovskite quantum dots (QDs) by using ab ifunctional ligand, L-phenylalanine (L-PHE). Through the addition of this ligand into the precursor solution during synthesis,t he in situ treated CsPbI 3 QDs displays ignificantly reduced surface states,i ncreased vacancy formation energy,higher photoluminescence quantum yields,and muchimproved stability.Consequently,the L-PHE passivated CsPbI 3 QDs enabled the realization of QD solar cells with an optimal efficiency of 14.62 %a nd red lightemitting diodes (LEDs) with ah ighest external quantum efficiency (EQE) of 10.21 %, respectively,d emonstrating the great potential of ligand bonding management in improving the optoelectronic properties of solution-processed perovskite QDs.

To fine-tune surface ligands towards high-performance devices,wedeveloped an in situ passivation process for all-inorganic cesium lead iodide (CsPbI 3)perovskite quantum dots (QDs) by using ab ifunctional ligand, L-phenylalanine (L-PHE). Through the addition of this ligand into the precursor solution during synthesis,the in situ treated CsPbI 3 QDs displays ignificantly reduced surface states,i ncreased vacancy formation energy,h igher photoluminescence quantum yields, and muchi mproved stability.C onsequently,t he L-PHE passivated CsPbI 3 QDs enabled the realization of QD solar cells with an optimal efficiency of 14.62 %a nd red light-emitting diodes (LEDs) with ah ighest external quantum efficiency (EQE) of 10.21 %, respectively,d emonstrating the great potential of ligand bonding management in improvingt he optoelectronic properties of solution-processed perovskite QDs.

We performed side-chain fluorination and alkylthio substituent in a template conjugated polymer and further investigate their impact on polymer–polymer solar cell performance.

HIGHLIGHTS• The introduction of hydroiodic acid (HI) manipulates the dynamic conversion of PbI 2 into highly coordinated species to optimize the nucleation and growth kinetics.• The addition of HI enables the fabrication of CsPbI 3 perovskite quantum dots with reduced defect density, enhanced crystallinity, higher phase purity, and near-unity photoluminescence quantum yield.• The efficiency of CsPbI 3 perovskite quantum dot solar cells was enhanced from 14.07% to 15.72% together with enhanced storage stability.