Abstract
Metal halide perovskite light-emitting diodes (LEDs) have achieved great progress in recent years. However, bright and spectrally stable blue perovskite LED remains a significant challenge. Three-dimensional mixed-halide perovskites have potential to achieve high brightness electroluminescence, but their emission spectra are unstable as a result of halide phase separation. Here, we reveal that there is already heterogeneous distribution of halides in the as-deposited perovskite films, which can trace back to the nonuniform mixture of halides in the precursors. By simply introducing cationic surfactants to improve the homogeneity of the halides in the precursor solution, we can overcome the phase segregation issue and obtain spectrally stable single-phase blue-emitting perovskites. We demonstrate efficient blue perovskite LEDs with high brightness, e.g., luminous efficacy of 4.7, 2.9, and 0.4 lm W−1 and luminance of over 37,000, 9,300, and 1,300 cd m−2 for sky blue, blue, and deep blue with Commission Internationale de l'Eclairage (CIE) coordinates of (0.068, 0.268), (0.091, 0.165), and (0.129, 0.061), respectively, suggesting real promise of perovskites for LED applications.
Highlights
Low-temperature solution-processed halide perovskite light-emitting diodes (LEDs), which can present high brightness and efficient electroluminescence (EL) with good colour purity [1, 2], show great application potential in lighting and displays
Perovskite LEDs can be an important technology for emerging displays, such as augmented and virtual reality displays, where usually a brightness of over 10,000 cd m-2 is required in pixel areas [3]
Blue EL with high peak EQE has been demonstrated based on low-dimensional perovskites [9, 10], though the devices suffer from low brightness due to the poor charge transport and serious efficiency roll-off at high current density caused by nonradiative Auger recombination [11]
Summary
Low-temperature solution-processed halide perovskite LEDs, which can present high brightness and efficient electroluminescence (EL) with good colour purity [1, 2], show great application potential in lighting and displays. High efficiency EL at very high brightness has been demonstrated in near-infrared and green perovskite LEDs [4,5,6]. Spectrally stable blue perovskite LEDs with high brightness are difficult to achieve. Blue EL with high peak EQE has been demonstrated based on low-dimensional perovskites [9, 10], though the devices suffer from low brightness due to the poor charge transport and serious efficiency roll-off at high current density caused by nonradiative Auger recombination [11]. Liu et al demonstrated efficient blue perovskite LEDs based
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