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Among the lead halide perovskite (LHP) family, CsPbI 3 is known to be significantly vulnerable to moisture, which hinders its use in real device applications. It is reported that chalcogen-based ligands can better stabilize CsPbI 3 and revive nanocrystals (NCs). Here, diphenyl diselenide (DPhDSe) ligand is used to revive the degraded CsPbI 3 NCs through a post-synthetic treatment of adding a small amount of DPhDSe in the degraded NC dispersion. DPhDSe in the dispersion formed nanofibrillar crystals at a low temperature through the π-π stacking of the phenyl ring. The nanofibrils played as a template on which the NCs self-assembled and they are attached side-by-side to form microfibers. The microfiber powder containing the NCs is optically stable at ambient conditions and morphologically self-healable by mild thermal annealing due to the dynamic Se─Se bond. The mechanism of the structural changes, optical transitions, and chemical changes has been systematically characterized through electron microscopy, diffraction, spectroscopy, and elemental analysis., (© 2024 Wiley‐VCH GmbH.)

Nitrogen-doped carbon dots (NCDs), exhibiting strong yellow emission in aqueous solution and solid matrices, have been utilized for fabricating heterostructure white electroluminescence devices. These devices consist of nitrogen-doped carbon dots as an emissive layer sandwiched between an organic hole transport layer (PEDOT:PSS) and an array of rutile TiO 2 nanorods, acting as an electron transport layer. Under an applied forward bias of 5 V, the device exhibits broadband electroluminescence covering the wavelength range of 390-900 nm, resulting in pure white light emission characteristics at room temperature. The result demonstrates the successful fabrication of all solution-processed, low-cost, eco-friendly NCDs-based LEDs with CIE (Commission Internationale d'Éclairage) coordinate of (0.31, 0.34) and color rendering index (CRI) > 90, which are close to ideal white light emission characteristics. The device functionalities are achieved based on defect-related NIR emission from TiO 2 nanorods array and visible emission from nitrogen-doped carbon dots. This result paves a new opportunity to develop low-cost, solution-processed nitrogen-doped carbon dots based on warm White light emitting diodes with high CRI for large-area display and lighting applications., (© 2023 IOP Publishing Ltd.)

Although α-CsPbI 3 is regarded as an attractive optical luminophore, it is readily degraded to the optically inactive δ-phase under ambient conditions. Here, we present a simple approach to revive degraded ("optically sick") α-CsPbI 3 through "medication" with thiol-containing ligands. The effect of different types of thiols is systematically studied through optical spectroscopy. The structural reconstruction of degraded α-CsPbI 3 nanocrystals to cubic crystals in the presence of thiol-containing ligands is visualized through high-resolution transmission electron microscopy and supported by X-ray diffraction analysis. We found that 1-dodecanethiol (DSH) effectively revives degraded CsPbI 3 and results in high immunity towards moisture and oxygen, hitherto unreported. DSH facilitates the passivation of surface defects and etching of degraded Cs 4 PbI 6 phase, thus reverting them back to the cubic CsPbI 3 phase, leading to enhanced PL and environmental stability., (© 2023 Wiley-VCH GmbH.)