Abstract
Looking beyond energy harvesting, metal-halide perovskites offer great opportunities to revolutionise large-area photodetection technologies due to their high absorption coefficients, long diffusion lengths, low trap densities and simple processability. However, successful extraction of photocarriers from perovskites and their conversion to electrical signals remain challenging due to the interdependency of photogain and dark current density. Here we report hybrid hetero-phototransistors by integrating perovskites with organic semiconductor transistor channels to form either “straddling-gap” type-I or “staggered-gap” type-II heterojunctions. Our results show that gradual transforming from type-II to type-I heterojunctions leads to increasing and tuneable photoresponsivity with high photogain. Importantly, with a preferential edge-on molecular orientation, the type-I heterostructure results in efficient photocarrier cycling through the channel. Additionally, we propose the use of a photo-inverter circuitry to assess the phototransistors’ functionality and amplification. Our study provides important insights into photocarrier dynamics and can help realise advanced device designs with “on-demand” optoelectronic properties.
Highlights
Research efforts have since been put into devices based on single crystals[23], single-crystalline layers[24] and monolayer flakes[25]
We systematically investigate charge transfer and photocarrier transport properties based on a conceptual heterojunction phototransistor (HJPT) architecture, employing the mixed-cation mixed-anion perovskite, FA0.83Cs0.17PbI2.7Br0.3 (FACs, FA = formamidinium)[13] as the light absorber material and two types of high-mobility p-type organic semiconductors (OSCs) {the small molecule 2,7-dioctyl[1]benzothieno [3,2-b][1]benzothiophene (C8-BTBT)[26] and the conjugated polymer indacenodithiophenebenzothiadiazole (C16-IDTBT)27}, as well as their blends, as the conducting channel materials
The absorption edge for FACs appears slightly below 800 nm whilst those of C8-BTBT and C16-IDTBT/blend 1:1 start at ~400 nm and ~730 nm, respectively
Summary
Research efforts have since been put into devices based on single crystals[23], single-crystalline layers[24] and monolayer flakes[25]. We systematically investigate charge transfer and photocarrier transport properties based on a conceptual heterojunction phototransistor (HJPT) architecture, employing the mixed-cation mixed-anion perovskite, FA0.83Cs0.17PbI2.7Br0.3 (FACs, FA = formamidinium)[13] as the light absorber material and two types of high-mobility p-type organic semiconductors (OSCs) {the small molecule 2,7-dioctyl[1]benzothieno [3,2-b][1]benzothiophene (C8-BTBT)[26] and the conjugated polymer indacenodithiophenebenzothiadiazole (C16-IDTBT)27}, as well as their blends, as the conducting channel materials. In our type-I HJPT, the long-lived photocarriers in the MHP can propagate along the OSC with minimum recombination losses, resulting in the enhanced photoresponse. We believe that this concept is not limited to the materials used in this work; rather, it could be extended to resolve undesired interfacial losses in other types of hybrid phototransistors.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
