Enhanced Piezoelectricity of MAPbI3 by the Introduction of MXene and Its Utilization in Boosting High‐Performance Photodetectors

Recently, perovskite photodetectors (PDs) are risen to prominence due to substantial research interest. Beyond merely tweaking the composition of materials, a cutting-edge advancement lies in leveraging the innate piezoelectric polarization properties of perovskites themselves. Here, the investigation shows utilizing Ti₃C₂T_x, a typical MXene, as an intermediate layer for significantly boosting the piezoelectric property of MAPbI₃ thin films. This improvement is primarily attributed to the enhanced polarization of the methylammonium (MA⁺) groups within MAPbI₃, induced by the OH groups present in Ti₃C₂T_x. A flexible PD based on the MAPbI₃/MXene heterostructure is then fabricated. The new device is sensitive to a wide range of wavelengths, displays greatly enhanced performance owing to the piezo-phototronic coupling. Moreover, the device is endowed with a greatly reduced response time, down to millisecond level, through the pyro-phototronic effect. The characterization shows applying a -1.2% compressive strain on the PD leads to a remarkable 102% increase in the common photocurrent, and a 76% increase in the pyro-phototronic current. The present work reveals how the emerging piezo-phototronic and pyro-phototronic effects can be employed to design high-performance flexible perovskite PDs.