Piezo-phototronic effect in highly stable CsPbI3-PVDF composite for self-powered nanogenerator and photodetector

All inorganic cesium lead iodide (CsPbI3) is highly emerging in the fabrication of self-powered nanogenerators (NGs) and photodetectors (PDs) beyond the excellent performance in photovoltaic cells if it is used as one of the component in composite when engineering polymer such as PVDF is selected as an another component. In addition, the coupling of photoexcitation, semiconductor functionality and piezoelectric effect in CsPbI3 (CPI) and PVDF composite may advance the fields in piezo-phototronics which is explored in this work. Here, we report the preparation of CPI embedded PVDF composite (CPIP) film turns into excellent material for NG and PD fabrication. Notably, the utilization of PVDF as stabilizing layer of CPI protects the CPI from degradation in ambient environment and enhances the overall electroactive phase (FEA ~ 96%) in CPIP film owing to its intrinsic piezoelectric nature (β − and γ − phase). Moreover, we aim at unraveling the atomistic details of the interaction between CPI mainly driven by PbI2 and CsI terminated surfaces and PVDF by first-principle density functional theory (DFT) calculations. In a step further, we exclusively investigate the interfacial interactions in most of the probable directions for strain-engineered bound system leading in the significant bandgap decrement. The CPIP made NG exhibits superior piezoelectric output voltage (Voc) of 20 V and short circuit current (Isc) of 6 μA which is significantly higher than Neat PVDF based NG under compressive pressure. Besides, the CPIP based PD is highly sensitive to trace the visible light illumination as evidenced from response time (tON as ~ 2.4 s and tOFF as 1.1 s), photo responsivity ~0.3 mAW−1 and maximum detectivity 0.122 × 1010 Jones. Finally, the piezo-phototronic effect is realized in CPIP composite by fabricating a self-powered PD which exhibits a significant enhancement of ΔIsc ~ 57% that offers a promising potential in next generation piezotronic and optoelectronic application.