Highly Sensitive Weak-Light Positioning Detection Enabled by a P(VDF-TrFE)-Doped Perovskite Heterojunction

Self-powered position-sensitive photodetectors (PSDs) based on organic-inorganic hybrid perovskites show significant potential for optical communication and intelligent sensing. However, their practical applications are hindered by low position sensitivity and limited weak-light detection capability. Herein, we propose integrating the ferroelectric polymer P(VDF-TrFE) into a CH₃NH₃(MA)PbI₃ matrix to construct a Spiro-OMeTAD/MAPbI₃:P(VDF-Turf) heterojunction. Systematic optimization reveals that a 0.42 wt % P(VDF-Turf) doping concentration significantly enhances the built-in electric field, enabling zero-bias broadband position detection (405-780 nm) with excellent linearity (nonlinearity <15%). Under weak-light illumination (10 μW), the optimized PSD achieves an exceptional position sensitivity of 629.28 mV/mm. Significantly, the pyro-phototronic effect further improves lateral photovoltaic response by 107.5%, boosting position sensitivity to 1305.76 mV/mm and enhancing device efficiency. The heterojunction also exhibits superior photoresponse performance, including a high responsivity (R) of 1.18 × 10⁴ V/W, specific detectivity (D) of 2.99 × 10¹³ Jones, and rapid response times of 6.1/5.6 ms. Moreover, this PSD functions effectively across an electrode spacing range of 0.3-3 mm. While position sensitivity decreases markedly with increasing spacing, a substantial value of 240.29 mV/mm with acceptable nonlinearity is maintained even at 3.0 mm. More importantly, owing to a distinct evaluation mechanism, the photoresponse improves with larger electrode spacing, yielding a maximum R of 3.33 × 10⁴ V/W and D of 8.93 × 10¹³ Jones, respectively. This work presents a promising strategy for designing high-performance self-powered position sensors and elucidates the underlying pyro-photovoltaic coupling mechanism in ferroelectric polymer doped perovskite composites.