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The mixed‐metal quaternary chalcohalides of group IV and V elements are a promising class of low‐toxicity perovskite‐inspired materials with tunable bandgaps and desirable defect tolerance. Sn2SbS2I3 is known for its broadband absorption, low exciton binding energy, ambient stability, and solution processability in thin films. However, its use in optoelectronic devices has so far been only limited to solar cells. In this work, the first self‐powered photodetectors based on Sn2SbS2I3 thin films, sandwiched in an n–i–p device configuration are reported. The insertion of an interlayer at the hole‐transport layer/gold top‐electrode interface reduces the dark current and improves the device performance. The high external quantum efficiency of the devices in the range of 350−900 nm hints to a broadband spectral photoresponsivity. The devices indeed exhibit promising photodetection properties, namely a photoresponsivity of 0.33 A W−1, a specific detectivity of 1.55 × 1012 Jones, and photoresponse/decay times of 0.52 and 0.45 s at zero bias voltage. These results, combined with the excellent operational stability of the photodetectors, encourage the exploration of a wide range of practical light‐sensing applications for quaternary chalcohalides and stimulate device and material engineering to further enhance photodetection across the UV‐Visible‐NIR spectrum. [ABSTRACT FROM AUTHOR]

Ag3BiI6 (ABI) is one of the most widely explored lead‐free perovskite‐inspired materials for eco‐friendly solar cell applications. However, despite the intense research efforts, the photovoltaic performance of ABI‐based devices remains very modest, primarily due to poor film morphology and ineffective charge extraction. This work aims at investigating the potential benefits of a thermally evaporated cesium iodide (CsI) interlayer on the performance of ABI‐based solar cells. Upon the addition of CsI atop the ABI layer in the device stack, the solar cells deliver a power conversion efficiency (PCE) of 2.27%. This is the highest efficiency reported for ABI solar cells employing a similar device architecture. It is found that the enhancement in PCE is largely due to improvement in the ABI|hole transport layer interface upon the introduction of CsI interlayer. The improvement is largely ascribed to enhanced surface coverage upon introduction of CsI interlayer, as evidenced by our comprehensive microscopy studies. Furthermore, impedance spectroscopy analysis is employed to provide further insights into the changes in charge transfer dynamics interlayer that dictate the enhancement of fill factor and short‐circuit current density in the devices. The findings indicate that the addition of CsI promotes charge transfer and minimizes recombination losses. [ABSTRACT FROM AUTHOR]

Growing oriented and monocrystalline layers of lead halide perovskites over device substrates helps to harness their outstanding optoelectronic properties. Epitaxial growth of lead halide perovskites for device fabrication is limited by the lack of lattice-matched substrates and the requirement of compact pinhole-free films. Most optoelectronic devices use amorphous substrates, hindering oriented epitaxial growth. Herein, highly crystalline methylammonium lead iodide (MAPbI3) thin films over amorphous substrates are demonstrated by meticulously optimizing the nucleation and growth kinetics in spin-coating. The "epitaxial-like" films enable large-area crystalline layer fabrication, with larger than 100 μm spherulitic grains oriented along [200] and [224] planes. The compact, highly crystalline, and oriented films of MAPbI3 formed over indium tin oxide/SnO2 are used to fabricate perovskite solar cells (PSCs) with an area of 1 cm². Despite the perovskite films being highly oriented and crystalline, the PSCs' performances highlight the critical role the interfaces play in photovoltaic cells. [ABSTRACT FROM AUTHOR]