Self-Powered Cu2ZnSnS4/CuI Type-I Heterojunction for Flexible and Broadband Photodetection Applications

Abstract

Self-powered devices that do not demand an external source of energy are becoming ever more attractive alternatives. The principle of such devices relies on the use of natural electric fields, which are highly effective in carrier separation. Flexible photodetectors are used in wearable electronics in which flexibility is of utmost importance. For this purpose, our research focuses on a paper-based Copper Zinc Tin Sulfide/Copper (I) Iodide type-I heterostructure photodetector prepared by using the successive ionic layer adsorption and reaction technique. The surface nanostructures of the photodetector are confirmed by SEM images, whereas the crystal structures of the material contain two phases, which are confirmed by XRD analysis. Moreover, optical absorption spectroscopy covers a wide range of wavelengths, showing bandgap energies of 3.55 eV for CuI and 1.12 eV for Cu₂ZnSnS₄ (CZTS). The detector has risen and falls in the range of 2.78–5.47 s at zero bias (0 V), with a maximum responsivity of 8.79 mA/W (1 mV) and a maximum specific detectivity of 1.08 × 10⁸ Jones across the entire broadband spectrum. This detector is considered an efficient and sustainable technology due to its self-powering functionality, its flexibility, its fabrication at ambient temperatures, and its unique ability to detect across the entire spectrum. Furthermore, it is reliable due to its consistency in performance after 3000 bending cycles. The CZTS/CuI detector has an optimal blend of properties suitable for wearable and energy-efficient optoelectronics through its effective integration of autonomous functionality, wide spectral detection, and mechanical flexibility.