Unraveling the Relevance of Electron and Hole Transfer in Lead Halide Perovskite Nanocrystals on Current Conduction

Optimization of perovskite-based optoelectronic performancedemandsprudent engineering in the device architecture with facile transportof generated charge carriers. Herein, we explore the charge transfer(CT) kinetics in perovskite nanocrystals (PNCs), CsPbBr3, with two redox-active quinones, menadione (MD) and anthraquinone(AQ), and its alteration in halide exchanged CsPbCl3. Witha series of spectroscopic and microscopic measurements, we infer thatboth electron and hole transfer (ET-HT) prevail in CsPbCl3 with quinones, resulting in a faster CT, while ET predominatesfor CsPbBr3. Furthermore, current-sensing atomic forcemicroscopy measurements demonstrate that the conductance across ametal-PNC-metal nanojunction is improved in the presenceof quinones. The contributions of ET and HT to current conductionacross PNCs are well supported and validated by theoretical calculationsof the density of states. These outcomes convey a new perspectiveon the relevance of ET and HT in the optimal current conduction andoptoelectronic device engineering of perovskites.