Engineering Chemical Vapor Deposition for Lead‐Free Perovskite‐Inspired MA₃Bi₂I₉ Self‐Powered Photodetectors with High Performance and Stability

Abstract

Lead‐free perovskite‐inspired materials (PIMs) have attracted great interest in optoelectronics, as they feature electronic properties similar to mainstream lead‐based perovskites but are not burdened by the same toxicity issues. However, PIM photodetectors to date have not delivered efficiencies and stability on par with benchmark technologies. With a focus on methylammonium bismuth iodide (MA3Bi2I9)—a prominent lead‐free PIM—this study overcomes this challenge by growing the photoactive material through an engineered chemical vapor deposition (CVD) approach. While the commonplace one‐tube (1T)‐CVD approach delivers films with disconnected grains and large pinholes, a two‐tube (2T)‐CVD approach is developed that enables the growth of smoother films with superior, compact morphology. The considerable optoelectronic potential of 2T‐CVD MA3Bi2I9 films is demonstrated by realizing high‐performance self‐powered photodetectors, which deliver a responsivity and specific detectivity as high as 0.28 A W–1 and 8.8 × 1012 Jones, respectively, under UV illumination—i.e., approximately twice as large as the 1T‐CVD counterparts. Further, nonencapsulated 2T‐CVD devices exhibit considerable long‐term moisture stability, with an attenuation of their photoresponse of ≤3% over 100 days. These results demonstrate that 2T‐CVD offers a promising platform that can catalyze the development of high‐performance lead‐free perovskite‐inspired optoelectronics.

Inkjet printing of heavy-metal-free quantum dots-based devices: a review

“…PQDs show exceptional tolerance for defects, strong optical absorption, low exciton binding energy, a long carrier diffusion length, and versatile processibility. To reduce the toxicity of PQDs, Pb has been replaced by Group 14 elements (Sn [87] and Ge [88]), Group 15 elements (Sb [89], Bi [90]), and monovalent and trivalent elements (double halide perovskite A 2 BB'X 3 ; B = B + , B' = B 3+ ) [91] to prepare LFP QDs. Figure 5(c) illustrates the structures of single and double halide perovskites [92].…”

Roadmap on printable electronic materials for next-generation sensors

“…A linear relationship between photocurrent and incident optical power in photodetectors is highly sought after for photometric purposes. However, with only a few exceptions [89,94], many lead-free-perovskite photodetectors developed to date exhibit a sublinear response [98,99]. Therefore, a key challenge is to identify and overcome the microscopic causes of this sublinear behavior in order to achieve a linear dynamic range competitive with incumbent photodetectors technologies.…”

Zero-bias Bi-based perovskite image sensor arrays with direct laser-scribing process

“…Among all the reported Pb-replacement materials, the low-toxicity trivalent cations Bi 3+ near the main group with Pb 2+ have attracted significant attention as potential candidates because they have the same 6s 2 electronic configuration, 24–26 and their electronegativity and ionic radius are comparable to those of Pb. 23,27–29 In addition, the Bi-based perovskites possess remarkable robustness in ambient atmospheric conditions, 30–33 long carrier diffusion lifetime, 34,35 and large light absorption coefficient, 36,37 suggesting that Bi is a hopeful candidate for light absorber in image sensors.…”