Boosting Electronic Properties of CsPbBr3 Nanocrystals via Lithium‐Ion Doping and Surface Passivation for Enhanced Electrical Conductivity and Efficient White Light‐Emitting Diodes

Lithium's interaction with CsPbBr₃ nanocrystals (NCs), can enhancing its intrinsic electrical conductivity (σ) for high-performance device applications. Herein, two distinctly different modes of Li⁺ interaction with CsPbBr₃ NCs: minor lattice insertion (0.07% relative to Cs) and predominant surface passivation is reported through Li_mPb_n alloy formation. In contrast, Li⁺ exhibits significantly reduced interaction with Cs₄PbBr₆ NCs, which could be due to the persence of lower amount of Pb²⁺ on the surface of these structures. The σ of CsPbBr₃:xLi⁺ NCs through bottom-contact devices exhibited a gradual increase from 2.1 × 10^-7 to as high as 2.5 × 10^-6 S m^-1, which is a 50-fold improvement compared to CsPbBr₃ NCs. The enhanced σ is attributed to the presence of Li⁺ doping and surface passivation of CsPbBr₃ by the Li_mPb_n ligated complexes. DFT calculations revealed electron movement from the valence and to conduction band and a reduced bandgap further supporting the inferences from experimental studies. The unique feature of the increased luminescence and σ of CsPbBr₃:Li⁺ NCs is explored for fabricating white light emitting diodes. The luminescence efficacy of the device is in the range of 88.5 to 112.5 lm W^-1 which is higher compared to pure CsPbBr₃ NCs (96.5 lm W^-1), offering a pathway for advanced optoelectronic applications.