Heterointerface engineering of tetragonal CsPbCl3 based ultraviolet photodetectors with pentacene for enhancing the photoelectric performance

Abstract

CsPbCl₃ has gained enormous attention since its discovery and showed great potential in ultraviolet photodetectors over the past few years. Processing CsPbCl₃ films through traditional solution methods hits a bottleneck due to their extremely poor precursor solubility. Here, high quality CsPbCl₃ films were fabricated through vacuum thermal evaporation without the limitation of solubility. The structure of the evaporated CsPbCl₃ films is a tetragonal phase with lattice constants different from those in common open source databases. The properties were thus first revealed by experimental characterization methods and theoretical calculations. Then, CsPbCl₃ based photodetectors were constructed with evaporated pentacene films as a heterointerface layer to suppress severe charge recombination at the interfaces. The dark current of these photodetectors based on CsPbCl₃–pentacene hybrid films decreases by more than two orders of magnitude, obtaining an enhanced on/off ratio, responsivity, and detectivity of 1.08 × 10⁶, 248 mA W⁻¹, and 2.04 × 10¹³ Jones with growth values of 34 000%, 35%, and 12 000%, respectively. These are benefitted greatly from the optimized surface morphology and carrier transport, which is evidenced by experiments and density functional theory (DFT) calculations. CsPbCl₃ based photodetector arrays were further constructed, achieving character recording. The additional pentacene film in the devices showed an effect on image denoising. Our work provides a feasible method for constructing high performance ultraviolet photodetectors, enlightening the significance of material combination for other optoelectronic devices.