SnSe Nanosheet-Based Microflowers for Flexible Paper Photodetectors with Efficient Broadband Visible–NIR Sensitivity

Flexible and eco-friendly photodetectors are crucial for next-generation wearable and low-power optoelectronics. Herein, we report the fabrication of a paper-based broadband photodetector functionalized with hydrothermally synthesized SnSe nanosheet-based microflowers (SnSe NSMF). A hand-printing approach was employed to form a SnSe NSMF layer on conductive graphite paper, followed by silver paste electrodes and PDMS encapsulation, enabling a simple and sustainable device architecture. Comprehensive characterizations (XRD, FESEM, Raman spectroscopy, EDS, XPS, UPS, UV–vis, and TEM) confirmed the high crystallinity, phase purity, and suitable band alignment of SnSe NSMF, ensuring efficient light absorption and carrier transport. The device exhibited a broadband photoresponse spanning 390–1100 nm, fast response and recovery times, and high responsivity and detectivity under a very low bias of 50 mV. Transient photocurrent measurements under varying light intensities further validated its reproducibility and stability. Importantly, the device also demonstrated sensitivity under infrared illumination, extending its application scope. This work highlights a low-cost, sustainable, and scalable route for fabricating flexible paper-based optoelectronics with promising applications in wearable sensors, broadband photodetection, and disposable photonic devices.