Picosecond multi-hole transfer and microsecond charge-separated states at the perovskite nanocrystal/tetracene interface

摘要

Hole transfer (HT) is often kinetically sluggish compared to electron transfer (ET), which increases recombination losses and thus limits the efficiency of many energy conversion devices such as light-emitting diodes, solar cells and solar-fuel production systems. Recently introduced lead halide perovskites and their nanocrystals (NCs) have emerged as an important class of energy conversion materials. Here we report that tetracene molecules can enable ultrafast and efficient HT from perovskite NCs. Transient absorption measurements reveal that HT occurs in 7.6 ± 0.2 ps, and the charge-separated states are extremely long-lived (5.1 ± 0.3 μs). Such exceptional charge separation properties are leveraged to demonstrate the dissociation of up to 5.6 excitons per NC by multi-hole transfer for the first time. These results not only suggest that tetracenes are an effective hole-extracting material for perovskite devices, but also have important implications for using perovskite NCs as sensitizers and tetracenes as redox mediators to drive single and even multi-electron photochemical reactions.