Effect of Ag nanoparticles on performance of CH3NH3PbI3 perovskite photodetectors

Highlights: • Utilizing Ag nanoparticles in the photodetectors based on CH₃NH₃PbI₃ perovskite films. • Different effects of Ag nanoparticles in the two CH₃NH₃PbI₃ perovskite photodetectors prepared using different precursors. • Enhanced performances of photodetectors synthesized from PbCl₂ and CH₃NH₃I by using Ag-nanoparticles-coated substrates. -- Abstract: Au and Ag nanoparticles (NPs) are often applied in inorganic and polymer photodetectors to enhance light-harvesting ability. Au NPs have been used in perovskite photodetectors and have shown good performance. The application of Ag NPs in perovskite photodetectors has not been previously reported. In this report, Ag NPs prepared by thermal evaporation deposition were introduced into CH₃NH₃PbI₃ perovskite photodetectors. The perovskite films were prepared using two kinds of precursor solutions. The morphology and crystallinity of the perovskite films changed greatly upon introducing Ag NPs. The performances of photodetectors based on the two kinds of perovskite films also changed when introducing Ag NPs. For the perovskite photodetector prepared from PbI₂ and methylammonium iodide, the responsivity decreased from 6.14 mA/W to 3.18 mA/W and the detectivity decreased from 2.68 × 10¹⁰ Jones to 1.21 × 10¹⁰ Jones, upon introducing Ag NPs. This was due to a less favorable film morphology and lower crystallinity when introducing Ag NPs. When PbI₂ in the precursor solution was replaced with PbCl₂, the device with Ag NPs had a higher responsivity, and a faster response time. The responsivity was 7.00 mA/W, which was four times higher than that of the device without Ag NPs. The detectivity of the device increased from 1.91 × 10¹⁰ Jones to 3.39 × 10¹⁰ Jones upon introducing Ag NPs.