Enhanced Piezoelectricity of MAPbI₃ by the Introduction of MXene and Its Utilization in Boosting High-Performance...

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.