Efficient Gate‐Tunable Hot‐Carrier Photocurrent from Perovskite Multiple Quantum Wells

Abstract Hot‐carrier relaxation above the bandgap results in significant energy losses, making the extraction of hot carriers a critical challenge for efficient hot‐carrier photocurrent generation in devices. In this study, we observe long‐lived hot carriers in the metal‐halide perovskite multiple quantum wells, (BA) 2 (MA) n −1 Pb n I 3 n +1 ( n = 3), and demonstrate effective hot‐hole photocurrent generation using 2D MoS₂ as an extraction layer. A high external quantum efficiency of short‐circuit hot‐carrier photocurrent of up to 35.4% is achieved. Further enhancement in photocurrent efficiency and open‐circuit photovoltage is achieved when a gate electric field is applied, resulting in an external quantum efficiency of up to 61.9%. Evidence of hot‐hole extraction is validated through operando transient reflection measurements on the working devices, with studies that depend on wavelength, carrier density, and gate voltage. DFT calculations on the heterostructure devices under different bias voltages further elucidate the mechanism of hot‐hole extraction enhancement. These findings underscore the potential of perovskite multiple quantum wells as long‐lived hot‐carrier generators and highlight the role of 2D transition metal dichalcogenide semiconductors as efficient hot‐carrier extraction electrodes for low‐power optoelectronics.