Defect Passivation via Additive Engineering to Improve Photodetection Performance in CsPbI₂Br Perovskite Photodetectors

Abstract

Solution-processable all-inorganic lead halide perovskites are under intensive attention due to their potential applications in low-cost high-performance optoelectronic devices such as photodetectors. However, solution processing usually generates structural and chemical defects which are detrimental to the photodetection performance of photodetectors. Here, a polymer additive of polyethylene glycol (PEG) was employed to passivate the localized defects in CsPbI 2 Br films through the Lewis acid−base interaction. The interfacial defects were passivated efficiently by introducing a trace amount of a PEG additive with a concentration of 0.4 mg mL −1 into the CsPbI 2 Br precursor solution, as suggested by the significantly reduced trap density of state, which was revealed using thermal admittance spectroscopy. Fourier transform infrared spectrum characterization showed that rather than Cs + or I − , a Lewis acid−base interaction was established between Pb 2+ and PEG to passivate the defects in the CsPbI 2 Br perovskite, which leads to large suppression of noise current. Both specific detectivity and linear dynamic range improved from 4.1 × 10 9 Jones and 73 dB to 2.2 × 10 11 Jones and 116 dB, respectively. Our work demonstrates the feasibility of employing an environmentally stable polymeric additive PEG to passivate defects for high photodetection performance in all-inorganic perovskite photodetectors.

A visible to near-infrared nanocrystalline organic photodetector with ultrafast photoresponse

“…2f, and it was obvious that the À3 dB cutoff frequency of devices based on D18:Y6 was determined to be 6.5 Â 10 4 Hz, which predicted a fast photo-response process. 37,38 The response time of the PD, a direct indication reflecting the PD performance, is also investigated. The rise time and decay time are defined as the interval in which the current increased from 10% to 90%, and transition from 90% down to 10% of the peak current, 24 respectively.…”

Improved Comprehensive Photovoltaic Performance and Mechanisms by Additive Engineering of Ti3C2Tx MXene into CsPbI2Br

“…In the last decade, the power conversion efficiency (PCE) of organic–inorganic hybrid perovskite solar cells (PSCs) has made great progress from 3.8 to 25.7%. , Meanwhile, hybrid PSCs suffer from unstable performance due to the decomposition of the fragile cations under thermal and/or moisture attack, which severely hinders the commercialization of the related solar cells. − Recently, Cs-based inorganic perovskites including CsPbI 3 , CsPbI 2 Br, and CsPbBr 3 without volatile organic components provide feasibility to fabricate inorganic PSCs with excellent thermal and light stability. Among them, CsPbI 2 Br is more promising due to its relatively appropriate bandgap (∼1.9 eV) and good α-phase stability in air. − …”

CsBr- and H2O-Enhanced CsPbI2Br for UV–NIR Dual-Mode Photodetector with High Responsivity

“…All inorganic perovskites have been used in photoelectric devices such as solar cells and PDs due to their excellent photoelectric properties such as an adjustable optical band gap, high absorption coefficient, high bipolar carrier transmission capacity, and high quantum yield. − CsPbI 2 Br perovskites with good phase stability and strong light absorption properties have been employed for PDs. − CsPbI 2 Br could not be degraded into its component salts and changed from a brown cubic phase to a yellow phase under the action of water vapor; this phase transition leads to a degradation of the device performance. Many efforts have been made to improve the performance of the CsPbI 2 Br perovskite. − Ma et al studied the effects of different stoichiometric ratios on the quality of CsPbI 2 Br perovskite films and found that CsBr can improve the stability of the films.…”