Giant Position-Sensitive Detection and Tunable ImagingEnabled by Piezo-Pyroelectric Coupling in Flexible Si NWs/CdS/ZnOHeterojunction

Abstract Position-sensitive detectors (PSDs), as noncontact precision positioning sensors based on the lateral photovoltaic effect (LPE), are predominantly limited to rigid substrates and surfer from critical drawbacks of low sensitivity, narrow spectral range, and poor environmental adaptability. In this work, we successfully design and fabricate a self-powered, high-sensitivity flexible PSD employing a Si nanowire (NW)/CdS/ZnO/ITO heterojunction, and systematically studied its LPE properties. Compared with conventional planar Si-based structures, the Si NW architecture delivers a remarkably enhanced LPE response, achieving a maximum position sensitivity of 498.9 mV/mm and an ultralow nonlinearity of merely 1.4%. The PSD also demonstrates a broad spectral response covering 450 to 1064 nm and an ultralarge working distance from 0.4 to 8 mm, highlighting superior wavelength adaptability and long-range detection capability. More importantly, we propose a novel LPE modulation mechanism via the synergistic coupling of lateral photovoltaic, pyroelectric, and piezoelectric effects. By harnessing the piezo-pyroelectric effect, the separation of photogenerated carriers is substantially promoted, yielding a dramatically enhanced sensitivity of 6868.7 mV/mm with an enhancement ratio of 1376%, outperforming reported values in rigid structures. In addition, the PSD achieves an ultrafast response speed, with rise and fall times of 68.8 and 86.1 μs, respectively. By further exploring the LPE responses under pulsed laser illumination with varied electrode spacings and bending states, we constructed an imaging system that leverages the distinct lateral photovoltage, the piezo-pyroelectric component, and the enhancement ratio. This system enables wavelength-resolved imaging and tunable brightness display, laying a practical foundation for the application of flexible PSDs in advanced optoelectronic detection fields.