Self-powered perovskite photodetector with chocolate-chip-cookie structure

Abstract

Photodetectors (PDs) are optoelectronic components that transform incident light into electrical output and are broadly applied in areas such as biomedical imaging, chemical sensing, light detection, and environmental monitoring. Although traditional PDs that use materials including Si, InGaAs, MoS<inf>2</inf>, and ZnO exhibit outstanding sensing performance, their production is expensive and complex. In contrast, perovskite-based PDs offer low-cost processability, bandgap tunability for light selectivity from the UV to IR wavelengths, and comparable detector performance. In addition, they can operate under zero-bias conditions (self-powered mode) via a photodiode configuration. In this study, we report a new hybrid perovskite-based self-powered (zero-bias) light sensor using a mixture of two perovskite materials with different band energies, exhibiting a “chocolate-chip-cookie” structure to achieve energy funnelling from one perovskite (chocolate chip) to another perovskite (cookie). By selecting CsPbBr<inf>3</inf> as the chip and Cs<inf>0.05</inf>FA<inf>0.81</inf>MA<inf>0.14</inf>Pb (I<inf>0.85</inf>Br<inf>0.15</inf>)<inf>3</inf> as the cookie, our device behaves like an energy-selective broadband photocurrent amplifier in self-powered mode by enhancing light detection in both the green and UV regimes (532 and 365 nm, respectively) through electric-field redistribution and energy-funnelling mechanisms. For these two wavelengths, the device achieves external quantum efficiencies of 69.39% and 47.38%, spectral responsivities of 0.30 and 0.14 A·W⁻¹, specific detectivities of 5.67 × 10¹² and 2.65 × 10¹² cm·Hz^1/2·W−1, and on/off ratios of 34 and 12, respectively. Furthermore, the charge-transfer mechanism is revealed by relevant characterisations.