Pivotal Role of Binding in Ultrafast Hole Transfer from CsPbBr3 Nanocrystals to Isomeric Diaminobenzenes

Abstract

Harnessing the full potential of perovskite nanocrystals (PNCs) in solar cells and photocatalytic applications demands a deep understanding of interfacial charge carrier transfer. This motivates the in-depth search for a suitable charge-transporting material that efficiently separates as well as extracts the charges of PNCs after photoexcitation. In spite of the large number of works in this direction, the understanding of the role of interfacial interaction in the hole extraction efficiency remains limited. In the present work, we have taken three structural isomers of diaminobenzenes (DABs), i.e., 1,2-diaminobenzene, 1,3-diaminobenzene, and 1,4-diaminobenzene, to explore the role of hole acceptor binding to the CsPbBr₃ NC surface in the hole transfer efficiency. With the help of steady-state/time-resolved photoluminescence and femtosecond transient absorption spectroscopic measurements, we proposed a pivotal role of interfacial binding in the hole transfer efficiency. A strong correlation between the association constant (K_a) and the hole transfer rate (k_ht) further strengthens our proposal. This finding is expected to pave the way for choosing better hole-transporting molecules for optoelectronic and photocatalytic application.