Carrier dynamics analysis of self-powered Sb2Se3 heterojunction photovoltaic detectors with a broad spectral response

Abstract

Simplifying device structures and reducing manufacturing costs are effective strategies for advancing the development of photovoltaic detectors. In this study, we have developed a self-powered heterojunction photovoltaic detector based on ZnO:B/Sb₂Se₃ through a combination of theoretical and experimental methods. Utilizing a close-spaced sublimation technique, we grew highly (002)-oriented high-light-sensitive Sb₂Se₃ on a wide-bandgap ZnO:B substrate to form a high-performance heterojunction. The multifunctional ZnO:B serves not only as an n-type layer forming a heterojunction structure for self-power generation but also acts as a transparent front electrode, streamlining the device structure. Simultaneously, through theoretical simulations, we investigated the impact of Sb₂Se₃ defects, interface defects, as well as the thicknesses of the ZnO:B layer and MoO₃ layer on the device’s performance. Notably, when the electron affinity of 4.1 eV in the ZnO:B layer minimizes the electron transport barrier for the Sb₂Se₃ layer, it results in the lowest carrier recombination rate and highest photocurrent density in the Sb₂Se₃ photovoltaic detector. The PCE of the photovoltaic detector has also reached its maximum. In addition, we determined the optimal thickness for the Sb₂Se₃ absorber, which varies with the monochromatic wavelength from 400- to 900-nm. Notably, longer wavelengths necessitate thicker absorbing layers. The longer the incident wavelength, the greater the impact of defect density on the device. Our exploration of the theoretical performance of the Sb₂Se₃ photovoltaic detectors revealed its exceptional detection capability at a wavelength of 700-nm, achieving a theoretical responsivity of 504.64 mA·W⁻¹, a detectivity of 1.34 × 10²⁰ Jones, and an on/off ratio of 1.14 × 10¹⁷. These results highlight the significant potential of ZnO:B/Sb₂Se₃ heterojunction photovoltaic detectors for future development.