Fast and Highly Sensitive Photodetectors Based on Pb‐Free Sn‐Based Perovskite with Additive Engineering

Abstract

Organic–inorganic halide perovskites have been widely investigated for the fabrication of photodetectors because of their excellent optoelectronic properties. However, the toxicity of Pb‐based perovskites and the lack of manufacturing technology in air limits the commercialization of perovskite‐based photodetectors. Tin halide perovskite (THP) is a promising candidate to replace Pb‐based perovskites due to its low toxicity and potential commercialization. However, THP suffers poor stability in air because Sn2+ is easily oxidized to Sn4+. This “self‐doping” effect not only degrades device performance rapidly, but also makes it difficult to fabricate THP‐based devices in air. Here, Pb‐free Sn‐based 2D perovskite PEA2SnI4 films with tin fluoride (SnF2) additive are prepared in air using a nitrogen quenching hot casting method. The photodetectors with an optimal SnF2 concentration of 20% exhibit a fast response speed of 0.56 ms and an excellent specific detectivity of 6.32 × 1013 Jones, the best combination of THP‐based photodetectors reported hitherto. The SnF2 additive is found to suppress the formation of Sn vacancies and improve the crystallinity of PEA2SnI4 films. The work provides an air‐processing technology of Pb‐free perovskite, which is easy to commercialize, and SnF2 additive engineering offering an effective way to demonstrate high performance photodetectors and image recognition applications.

High-Performance Lead-Free Layered-Perovskite Photodetectors and Bipolar Transistors by Solvent Engineering

“…The inclusion of SnF 2 enhances the chemical potential of tin, thereby increasing the energy required for Sn vacancy generation and preventing the oxidation of Sn 2+ . 24 The introduction of tin powder facilitates the reduction of Sn 4+ in the perovskite solution. This is particularly relevant as commercial SnI 2 may undergo slight oxidation during usage, and the addition of tin powder helps counteracting the initial production of Sn 4+ .…”

“…These observations indicate that SnF 2 acts as an oxidation inhibitor, while the addition of tin powder could reduce Sn 4+ to Sn 2+ . The inclusion of SnF 2 enhances the chemical potential of tin, thereby increasing the energy required for Sn vacancy generation and preventing the oxidation of Sn 2+ . The introduction of tin powder facilitates the reduction of Sn 4+ in the perovskite solution.…”

“…Seong and co-workers prepared a 2D perovskite (PEA) 2 SnI 4 thin film containing tin fluoride (SnF 2 ) additive in air by nitrogen quenching and hot casting. The photodetector with the optimized SnF 2 showed a fast response speed of 0.56 ms and an excellent specific detectivity of 6.32 × 10 13 Jones . The rise of these studies significantly broadened the application prospect of 2D tin-based perovskite photodetectors.…”

“…25 During the oxidation process, the generation of holes leads to p-type selfdoping, resulting in a high vacancy density of Sn and an increased dark carrier density. 24 Consequently, the photodetector suffers from a large dark current and low detectivity. More importantly, due to the rapid crystallization process of Sn-based perovskites, it is easy to form uneven and poorquality films.…”

Thermally Stable and Radiation‐Proof Visible‐Light Photodetectors Made from N‐Doped Diamond

“…In the past decades, visible-light photodetectors (PDs), including photoconductors, photodiodes, phototransistors, avalanche photodetectors, and quantum well detectors, have been demonstrated. [1,2] Narrow-to-medium bandgap (≈1-3.5 eV) DOI: 10.1002/adom.202203006 semiconductors, for example, Si, SiC, CdS, GaAs, ZnO, ZnSe, etc., were employed as an active layer in such visible-light PDs, showing satisfying performance under normal conditions of operation. [3][4][5][6][7] However, these visible-light PDs are low tolerance against high temperature, gamma-ray, and neutrons, and their solid-state imaging systems will deteriorate upon a total dose of 200 to 1000 Gy irradiations.…”