Fabrication of Highly Stable Fully-Inorganic Halide Perovskite Films for Optoelectronic Application

Despite the fact that stability is a critical issue affecting halide perovskite after the materials have been developed, these materials continue to be studied due to their outstanding optoelectronic characteristics such as narrow emission band width, high PLQY. Many methods are suggested and improved, but the limitations for the display and lighting applications are still remaining. Here, we propose the fabrication of stable cesium lead tri-halide (CsPbX₃; X= Cl, Br, I) perovskite films using photocurable polyurethane material, norland optical adhesive 63 (NOA 63), to generate white LEDs by placing films on the InGaN 450 nm blue chip. Comparing with the conventional perovskites, fabricated films well maintained the luminescence properties such as full widths at half maximum (FWHM) of 18 nm and 31 nm for green and red films, respectively. For the stability issue, pristine perovskite without encapsulation is decomposed immediately at high humidity and temperature, but NOA 63 encapsulated perovskite maintained a PL emission property of 60% after four hours in artificial atmosphere. The CIE color triangle reached ~119% of the NTSC standard, exhibiting high color purity. From the results, we confirm that the NOA 63 encapsulated halide perovskites are beneficial when applied in optoelectronic applications due to their improved stability and maintained characteristics.