Perovskite Multiple Quantum Wells on Layered Materials toward Narrow-Band Green Emission for Backlight Display Applications.

Quasi-two-dimensional perovskite multiple quantum wells (MQWs) have garnered attention on account of their good stability in comparison with three-dimensional analogs for light-emitting diode (LED) applications, but they exhibit a declined photoluminescence quantum yield (PLQY) for the backlight display technology. Herein, we report an in situ process by introducing layered materials as substrates to prepare the perovskite MQW powder and utilize hexagonal boron nitride (h-BN) as an example to investigate the luminescence characteristics and mechanism of h-BN@(PMA)2MAn-1PbnBr3n+1 (h-BN@PMPB). Remarkably, the deposition strategy enables an enhanced PLQY from 2.6 to 32.4%. A synergetic effect of low reabsorption, low defect concentration, and high absorptivity leads to high-efficiency cascade energy transfer and also an improvement in stability. Moreover, the h-BN@PMPB composite powder shows a narrow-band green emission band peaking at 532 nm with a full width at half maximum of 32 nm, and the white LED backlight reaches a wide color gamut 106.1% of the National Television Standards Committee (NTSC). This work reveals a general synthesis method for preparing perovskite powder and paves the way to achieve new solid-state luminescent materials with controlled size and morphology for backlight display applications.