Enhanced Charge Injection and Recombination of CsPbBr3 Perovskite Nanocrystals upon Internal Heterovalent Substitution

Heterovalently substituting the Pb(II) cation of CsPbBr3 perovskite nanocrystals (PNCs) with Sb(III) cation is developed as an internal engineering strategy to tailor their optoelectrical properties. Partially replacing Pb(II)-Br bonds of cubic CsPbBr3 PNCs with stronger Sb(III)-Br bonds not only can enlarge the bandgap and preserve the highly-passivated surface-states of parent PNCs, but also enables the obtained Sb(III)-CsPbBr3 PNCs with both blue-shifted and enhanced absorbance, photoluminescence and electrochemiluminescence as well as boosted electron and hole injection responses via electrochemical redox. The enhanced absorbance and radiative-charge-transfer originate from both the increased vacancies in crystals and the impurity states in the bandgap of PNCs upon substituting Pb(II) with Sb(III), because the increased vacancies are more favourable to recombine the electrons injected via photoexcitation and/or electrochemical redox, while suitable impurity states in the bandgap of PNCs also facilitat...