Brightening deep-blue perovskite light-emitting diodes: A path to Rec. 2020
Seungjae Lee, Seungjae Lee, Junho Kim, Hyojun Kim, Changwon Kim, Siin Kim, Changjo Kim, H. W. Lee, Bongjun Choi, Chinnadurai Muthu, T. Kim, Jihyung Lee, Jihyung Lee, Seungbok Lee, Seungbok Lee, Hyotcherl Ihee, Jung‐Yong Lee, Jung‐Yong Lee
Abstract
Deep-blue perovskite light-emitting diodes (PeLEDs) of high purity are highly sought after for next-generation displays complying with the Rec. 2020 standard. However, mixed-halide perovskite materials designed for deep-blue emitters are prone to halide vacancies, which readily occur because of the low formation energy of chloride vacancies. This degrades bandgap instability and performance. Here, we propose a chloride vacancy–targeting passivation strategy using sulfonate ligands with different chain lengths. The sulfonate groups have a strong affinity for lead(II) ions, effectively neutralizing vacancies. Our strategy successfully suppressed phase segregation, yielding color-stable deep-blue PeLEDs with an emission peak at 461 nanometers and a maximum luminance ( L max ) of 2707 candela per square meter with external quantum efficiency (EQE) of 3.05%, one of the highest for Rec. 2020 standard–compliant deep-blue PeLEDs. We also observed a notable increase in EQE up to 5.68% at L max of 1978 candela per square meter with an emission peak at 461 nanometers by changing the carbon chain length.