Enhanced Broadband Responsivity of Ni-Doped Sb₂Se₃ Nanorod Photodetector

Abstract

Antimony selenide (Sb2Se3) semiconductor with a narrow band gap is regarded as an ideal candidate for the next-generation broadband photodetectors. However, the photodetectors based on the binary Sb2Se3 semiconductor suffer from low responsivity (Rλ) and external quantum efficiency due to the intrinsic low electrical conductivity. To address the issue, we introduce a low-valence Ni cation (Ni2+) into the binary Sb2Se3 ((Sb1–xNix)2Se3) nanorods synthesized by a facile hot-injection process. With increasing Ni-doping concentration, the (Sb1–xNix)2Se3 nanorods exhibit a significant increase of electrical conductivity from 4.983 × 10–5 to 4.011 × 10–4 Ω–1 m–1. The photodetector based on (Sb0.995Ni0.005)2Se3 nanorod film exhibits an excellent responsivity of 18.9 mA/W under white light illumination of 45 mW/cm2 at an applied bias voltage of 3 V, which is an approximately 19-fold higher than that of the pristine Sb2Se3 nanorod photodetector. Moreover, the density functional theory calculation has demonstrated that the Ni2+ doped into Sb2Se3 will preferentially occupy the Sb site and introduce a shallow energy level of acceptor, resulting in the enhancement of electrical conductivity, which is consistent with the experimental result. Therefore, the work proves the substitution of Sb site with a low-valence metal cation into Sb2Se3 is an effective strategy to improve the performance of the Sb2Se3-based photodetector.