Speaker
Description
Metal halide perovskites combine high optical absorption coefficient, bandgap tunability, and the use of heavy atoms, making them attractive for photodetectors across the visible and X-ray range. However, most demonstrations rely on solution processing, which presents challenges in terms of reproducibility, substrate compatibility, and large-area uniformity. Vapor-based methods provide a scalable and controllable alternative, already established in the optoelectronics industry.
Here we report the fabrication of perovskite photodetectors by thermal co-evaporation of the halide precursors. This approach enables precise control of film thickness, stoichiometry, and morphology, yielding uniform, pinhole-free layers across centimeter-scale substrates. The process operates at low substrate temperature, allowing deposition of perovskites on temperature-sensitive substrates.
Devices based on co-evaporated perovskites show low dark and noise currents. In the visible range, they reach external quantum efficiency above 90%, and specific detectivity up to $5 \times 10^{12}$ Jones. Under X-ray irradiation, sensitivities exceed $33 \pm 4~\mu\text{C}\,\text{Gy}^{-1}\,\text{cm}^{-2}$ with a limit of detection of $2.0 \pm 1.6~\mu\text{Gy}\,\text{s}^{-1}$. Compared to solution-processed analogues, the vapor-grown devices exhibit enhanced reproducibility and stable operation under reverse bias. Examples of broadband detectors covering the visible spectrum, as well as narrowband selective detectors, will be presented to illustrate the versatility of the method.
In summary, co-evaporation provides a simple, scalable, and uniform route for preparing thin-film perovskite photodetectors. The combination of visible and X-ray sensitivity, tunable spectral selectivity, and robust performance highlights its potential for emerging imaging and sensing technologies.
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