Investigation on the stability improvement of hybrid halide all-inorganic perovskite quantum dots

Abstract

Perovskite quantum dots (QDs) with stable luminous properties are crucial to for the construction of corresponding light-emitting diodes (LEDs). Hybrid halide perovskite QDs, especially those contain iodine element emitting red light, usually demonstrate poor emission stability owing to the halide segregation. Moreover, red component is indispensable for the construction of white LEDs (WLEDs). Hence, it is essential to improve the luminous stability of hybrid halide perovskite QDs containing iodine element. Here, magnesium dopant and silica matrix were employed to improve the stability of hybrid halide CsPb(IBr)3 QDs. Red, green and blue are three primary colors for constructing WLEDs. Therefore, silica-coated CsPbBr3 QDs emitting green light were also synthesized. The fabricated silica-coated Mn:CsPb(IBr)3/PMMA film delivered good emission stability during a 42 d observation period, exhibiting the improved stability compared with the corresponding Mn:CsPb(IBr)3 QDs in solution. WLEDs were fabricated by integrating the mixture of silica-coated Mn:CsPb(IBr)3 QDs, silica-coated CsPbBr3 QDs and silicon sealant with a blue-emission LED chip. The as fabricated device exhibited a longer lifetime to be lit than that of those reported previously. During the 36 d observation period for the as fabricated device, the red emission from the silica-coated Mn:CsPb(IBr)3 QDs experienced a peak-emission shift of 34 nm, which is much less than that in Mn:CsPb(IBr)3 QDs solution. Their overall intensity downtrend combined the peak-emission shift are responsible for the spectrum shape change, so as to the fluctuation of color correlated temperature and color rendering index. Our study provides a good starting point for the further improvement of the stability of the hybrid halide perovskites QDs and the corresponding light-emitting devices. With deep studies on the synthesis method and luminous mechanism for hybrid halide CsPb(IBr)3 QDs, red-emission perovskite QDs with satisfied properties are expected to be obtained.