Dual passivation effect of a C60-capped and Zn2+-doped CsPbCl3 perovskite photodetector

Abstract

In this study, the divalent metal dopant cation of Zn²⁺ and a surface capping layer of C₆₀ were simultaneously incorporated into a CsPbCl₃ perovskite on an Si/SiO₂ substrate, and the photoresponse performance of the CsPbCl₃-based photodetector was investigated. It was found that the doping ratio of ZnCl₂ and thickness of the C₆₀ capping layer exhibited significant influences on the photophysical features and photoresponse performances. With the optimal Zn²⁺ ratio of 11.0% and C₆₀ layer thickness of 10 nm, a wide wavelength range photoresponse from UV to NIR (350–1010 nm) was achieved with the optimal responsivity (R), detectivity D* and noise equivalent power (NEP) of 10 477 A W⁻¹, 2.09 × 10¹⁴ Jones (cm Hz^1/2 W⁻¹) and 4.16 × 10⁻¹⁰ W Hz^−1/2, respectively, at the incident light wavelength (λ) of 500 nm and 0.2 mW cm⁻² power. Meanwhile, the dependence of trap density and carrier mobility on Zn²⁺ concentration and C₆₀ layer thickness derived from the mode of space charge limited current (SCLC) with the lowest and highest values of 3.2 × 10¹⁵ cm⁻³ and 1.52 × 10⁻³ cm² V⁻¹ s⁻¹, respectively, at the optimal Zn²⁺ doping ratio and C₆₀ layer thickness demonstrated a dual-passivation effect from both Zn²⁺ and C₆₀. Such behavior may be attributed to the interaction between the A and B site species in the C₆₀-capped and Zn²⁺-doped CsPbCl₃, promoting the suppression of defects and restoration of structure. Meanwhile, the exciton binding energy (E_B) imposed a critical impact on the carrier dynamics and PL performance. Thus, the photoresponse is controlled by the combining effects of structure defects and exciton binding energy, both of which can be strongly modulated by the ZnCl₂ doping concentration and C₆₀ capping layer thickness.