Generation of Free Carriers in MoSe<sub>2</sub> Monolayers Via Energy Transfer from CsPbBr<sub>3</sub> Nanocrystals
Aswin Asaithambi, Nastaran Kazemi Tofighi, Nicola Curreli, Manuela De Franco, Aniket Patra, Nicolò Petrini, Dmitry Baranov, Liberato Manna, Francesco Di Stasio, Ilka Kriegel
Abstract
Abstract Transition metal dichalcogenide (TMDCs) monolayers make an excellent component in optoelectronic devices such as photodetectors and phototransistors. Selenide‐based TMDCs, specifically molybdenum diselenide (MoSe 2 ) monolayers with low defect densities, show much faster photoresponses compared to their sulfide counterpart. However, the typically low absorption of the atomically thin MoSe 2 monolayer and high exciton binding energy limit the photogeneration of charge carriers. Yet, integration of light‐harvesting materials with TMDCs can produce increased photocurrents via energy transfer. In this article, it is demonstrated that the interaction of cesium lead bromide (CsPbBr 3 ) nanocrystals with MoSe 2 monolayers results into an energy transfer efficiency of over 86%, as ascertained from the quenching and decay dynamics of the CsPbBr 3 nanocrystals emission. Notably, the increase in the MoSe 2 monolayer emission in the heterostructure accounts only for 33% of the transferred energy. It is found that part of the excess energy generates directly free carriers in the MoSe 2 monolayer, as a result of the transfer of energy into the exciton continuum. The efficiency of the heterostructure via enhanced photocurrents with respect to the single material unit is proven. These results demonstrate a viable route to overcome the high exciton binding energy typical for TMDCs, as such having an impact on optoelectronic processes that rely on efficient exciton dissociation.