Mobile Trions in Electrically Tunable Two-dimensional Hybrid Perovskites.

Two-dimensional, hybrid perovskites are currently in the spotlight of material research for light-harvesting and -emitting applications. It remains extremely challenging, however, to externally control their optical response due to the difficulties of introducing electrical doping. Here, we demonstrate an approach of interfacing ultrathin sheets of perovskites with few-layer graphene and hexagonal boron nitride into gate-tunable, hybrid heterostructures. We show bipolar, continuous tuning of light emission and absorption in 2D perovskites by electrically injecting carriers to densities as high as 10 12  cm -2 . It reveals the emergence of both negatively- and positively-charged excitons, or trions, with binding energies up to 46 meV, among the highest ones measured for 2D systems. Trions are shown to dominate light emission and propagate with mobilities reaching 200 cm 2 /(Vs) at elevated temperatures. Our findings introduce the physics of interacting mixtures of optical and electrical excitations to the broad family of 2D inorganic-organic nanostructures. The presented strategy to electrically control the optical response of 2D perovskites highlights it as a promising material platform towards electrically-modulated light-emitters, externally guided charged exciton currents, and exciton transistors based on layered, hybrid semiconductors. This article is protected by copyright. All rights reserved.