Modified α-Al2O3 wafer: Enhance the stability of perovskite quantum dots with wide colour gamut for white light-emitting diodes

Recently, perovskite has received extensive attention due to their excellent photoelectric properties, while the instability of perovskite quantum dots (PQDs) has always troubled us. Herein, we proposed a simple coating mechanism to protect PQDs. Using oleic acid (OA) for etching α-Al 2 O 3 wafer to make the surface appear pore structure, and the PQDs was coated within the modified α-Al 2 O 3 wafer, thereby improving the stability of PQDs. The CsPbX 3 @α-Al 2 O 3 composite material can achieve the emission of blue-green–red (436 nm to 636 nm) through adjustable luminescence wavelength. The photoluminescence (PL) intensity of CsPbBr 3 @α-Al 2 O 3 composite material exposure to the air after 28 days can maintain over 50%. It is worth noticing that the photoluminescent quantum yield (PLQY) of CsPbBrI 2 @α-Al 2 O 3 composite material can reach 58%, the colour purity of CsPbBr 3 @α-Al 2 O 3 and CsPbBrI 2 @α-Al 2 O 3 achieve 97.1% and 99.8%, respectively. It was due to the high colour purity of the composite materials can the selected CIE colour coordinate monochromatic light encompassed 114% of NTSC colour gamut. Moreover, the warm white light-emitting diode (WLED) yielded bright natural white light and showed the luminous efficiency (LE) of 86.58 lm/W, colour rendering index (CRI) of 86.9, correlated colour temperature (CCT) of 4602 K. The LE and CRI reaches a relatively balanced value, which showed that this composite material has a certain development prospect in the WLED field.