Breaking bandgap limitation: Improved photosensitization in plasmonic-based CsPbBr3 photodetectors via hot-electron injection

A higher detection performance and stability are always pursued in the development of photoelectric or photo-electrochemical devices, critical for their further commercial application. Here, we report a CsPbBr3-based photodetector engineered from a multilayer Si/Ag islands/CsPbBr3/PMMA system, showing an evidently enhanced photosensitization and breaking the absorption edge of CsPbBr3. On the one hand, the photocurrent contribution from plasmonic hot-electron injection effectively extends the detection limit of our photodetectors much below the band edge of CsPbBr3, depending only on Schottky barrier. On the other hand, the surface plasmons on nanoscale silver islands can considerably improve the light harvesting ability of the CsPbBr3 layer, ascribed to the confinement of light in the adjacency of silver islands. Numerical simulations show the localized enhancement of light near silver islands, corresponding to the excitation of localized surface plasmon resonances. It shows a higher light intensity distribution inside the CsPbBr3 layer of the photodetector consisting of Si/Ag islands/CsPbBr3/PMMA with the photodetector with only Ag islands in accordance with their current–voltage(I–V) characteristics. Ultimately, our plasmonic CsPbBr3-based photodetector presents a >10-fold increase in the photocurrent and a doubling of the operating lifetime. Our work provides important insight into the realization of the performance and stability of optoelectronic devices based on plasmonics.