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Inorganic perovskites (CsPbX3, X = Cl, Br and I) have aroused great interest due to their extraordinary optoelectronic properties. Despite their rapid progress, device performances are hindered by the instabilities of perovskites. Herein, we employed a thermal co-evaporation method to prepare stable and compact CsPbCl3 films. These films could maintain stability in ambient air for 12 months. The effect of annealing temperature and annealing time on the CsPbCl3 films were researched. Films had high crystallinity and luminescent intensity with 3 μm large grains at optimal annealing condition. This result provides an insightful understanding of annealing process on CsPbCl3 films, as well as to offer a valuable approach for the future of optoelectronic devices based on perovskite materials.

Inorganic lead halide perovskites have gained extensive attention in a variety of optoelectronic applications. Herein, we prepared CsPbCl3 films with high crystallinity by thermal evaporation method and attempted to produce all-inorganic CsPbCl3 violet/blue LEDs for the first time. To enhance the luminescence performance, the influence of CsPbCl3 films thickness was discussed. The turn-on voltage of the device was about 3 V and current density could reach the maximum with high brightness at forward bias of 6 V. This work not only demonstrated a facile strategy to prepare high-quality CsPbCl3 perovskite films, but also provided an important insight in blue LEDs based on CsPbCl3 materials.

Copper Iodide (CuI) thin films were prepared by iodination technique. The transmission spectrum showed band gap of prepared CuI thin film was 3.0 eV. A main emission at 404 nm (near-band emission), a defect emission at 412 nm (CBM→VCu) and another defect emission at 710 nm (VI→CuI) were found in photoluminescence spectrum. Transition mechanism of CuI was proposed by low-temperature photoluminescence spectrum. Emission at 412 nm is greatly affected by ambient temperature. The results show that the thermal activation at room temperature inhibits the emission at 412 nm, and the inhibition decreases when the temperature dropped, resulting in an increase in emission intensity at 412 nm and a decrease in emission intensity at 710 nm.