Flexible Perovskite and Organic Semiconductor Heterojunction Devices for Tunable Band-Selective Photodetection

Abstract

Filter-free band-selective photodetectors with tunable band edges possess extensive applications in smart sensors, artificial intelligence, the internet of everything, and so forth. However, such photodetectors operated with the charge collection narrowing effect require a thick active layer over millimeters, leading to rather a large device size, high material cost, and limited mechanical flexibility. In this work, we report a flexible thin-film perovskite and organic semiconductor (OSC) heterojunction device, which can achieve adjustable band-selective photodetection by utilizing the easy tunability of the perovskite band gap. First, heterojunction photodiodes with only two active layers of perovskites and OSCs are fabricated, in which the perovskite contributes to light absorption and rectification characteristics simultaneously. The fundamental device operation mechanism is investigated by combining the band alignments of the heterojunctions and their potential distributions observed with Kelvin probe force microscopy. It uncovers that the presence of built-in electric fields in the heterojunctions caused by moderate band alignments and appropriate difference in hole and electron concentrations between the perovskites and the OSCs is significant for the properties of the photodiodes. The resultant photodiodes exhibit a high rectification ratio of up to 10 3 , decent photodetection performance, and mechanical flexibility. Furthermore, photodetectors based on perovskite/OSC/perovskite stack heterojunctions can realize the functions of filterless band-selective photodetection in a single device, and the band edges in the photodetection can be modulated by tuning the perovskite band gap. Therefore, this work provides flexible thin-film photodiodes with the potential of miniaturization and low-cost fabrication and demonstrates tunable band-selective photodetection for advanced applications.

Recent progress in construction methods and applications of perovskite photodetector arrays

“…These commonly available materials are polyvinyl alcohol (PVA), polyester (PET), polyimide (PI), polynaphthalene dimethyl ethylene glycol (PEN), textile materials, etc. 52,[118][119][120][121] Huang et al introduced a flexible 10 Â 10 perovskite photodetector array on the PI substrate by developing inkjet printing technology for color detection. 93 Each pixel with a photoconductor structure of Au/ perovskite/Au consisted of three sub-pixels.…”

Recent Application and Progress of Metal Halide Perovskite Photodetector on Flexible Substrates

“…Various organic materials such as organic semiconductors and dyes are often used for hybridization with metal halide perovskite materials. [ 73‐74 ] Moreover, as the functional inorganic materials for heterojunction formation by hybridization with perovskite, carbon nanotubes, metallic oxides, MXene, MoS 2 , etc ., have been extensively studied in FPPDs. [ 27,75‐79 ]…”

“…In 2022, Tingting Zhang et al . [ 73 ] reported a thin film perovskite and organic semiconductor (OSC) heterojunction device that can utilize the tunable bandgap of perovskite to achieve tunable band‐selective photodetection. First, heterojunction photodiodes with only two layers of perovskite and OSC were fabricated, where the perovskite promotes both optical absorption and rectification properties.…”

Flexible Microspectrometers Based on Printed Perovskite Pixels with Graded Bandgaps

“…Miniaturized spectrometers with advantages of portability and low cost and power consumption have attracted much attention due to their potential in advanced application scenarios, including wearable devices, hyperspectral imaging, and internet of things. − Computational spectrum reconstruction based on a series of response-modulated photodetectors with a gradient bandgap is one of the most promising methods for achieving such miniaturized spectroscopy systems. − For instance, Yang et al successfully demonstrate a miniaturized spectrometer at the scale of tens of micrometers using a single compositionally graded CdS x Se 1– x nanowire . Recently, halide perovskites have also been used in photodetectors for human visual-like spectrum projection, full-color detection, and multispectral recognition owing to their outstanding properties such as facile solution-process fabrication, excellent light harvesting coefficients, and tunable bandgaps. − Xu et al demonstrated a miniaturized multispectral detector based on a composition-gradient perovskite microwire detector array, offering a response edge ranging from 450 to 790 nm . However, such technologies require customized epitaxial growth for the composition-gradient micro/nanowire semiconductors followed by transfer of a single nanowire on the device substrate, which inevitably results in large-scale fabrication, which remains challenging.…”