High Radiance of Perovskite Light‐Emitting Diodes Enabled by Perovskite Heterojunctions

Abstract

Metal-halide perovskites (MHPs) have made incredible achievements in the past few years, especially in the area of perovskite light-emitting diodes (PeLEDs). Nevertheless, hole transport layers (HTLs) used in most highly efficient PeLEDs usually have low hole mobilities in the range of 10 −4 -10 −6 cm 2 V −1 s −1 , much lower than that of MHPs, resulting in severe roll-off and low radiance of the devices. Here, methylammonium lead iodide (MAPbI 3 ) is successfully deposited on top of methylammonium lead chloride (MAPbCl 3 ) using orthogonal solvent to form heterojunction PeLEDs (HJ-PeLEDs). Due to the high hole mobility of MAPbCl 3 ≈42 cm 2 V −1 s −1 , the HJ-PeLEDs exhibit a peak external quantum efficiency of 10.7% and a high radiance of 157 W sr −1 m −2 at a low applied voltage of 3.9 V. Furthermore, the large-area (28 cm 2 ) HJ-PeLEDs made by blade coating shows a uniform and high radiance of ≈180 W sr −1 m −2 . This work provides a novel strategy to fabricate bright and large-area PeLEDs to meet the requirements of commercial applications.

Spatial Control of the Hole Accumulation Zone for Hole-Dominated Perovskite Light-Emitting Diodes by Inserting a CsAc Layer

“…It is worth noting that the current density of a working PeLED is determined by the minority carrier. 40 Therefore, the current density shown in Figure 1b shows minor differences between PeLEDs without and with the CsAc layer after turning on.…”

“…After incorporating the CsAc layer, the hole accumulation is considered to shift from the perovskite/ETL interface to the HTL/CsAc interface, leading to a reduction of the capacitance due to a larger distance between the accumulated holes and electrons. It is worth noting that the current density of a working PeLED is determined by the minority carrier . Therefore, the current density shown in Figure b shows minor differences between PeLEDs without and with the CsAc layer after turning on.…”

Materials, Device Structures, and Applications of Flexible Perovskite Light‐Emitting Diodes

“…The excess electrons are often trapped at perovskite/ETL interfaces by various defects, reducing the electron-hole radiative recombination efficiency. [112] To solve this issue, chargetransport layers with similar charge mobilities have been used. Ling et al fabricated solution-processed green CsPbBr 3 PeLEDs with sandwiched structures (Figure 3e).…”

A novel heterojunction layer-assisted interfacial defect control strategy for high-performance solar cells

“…Metal halide perovskites are highly promising materials for photovoltaic (PV) applications in view of their appealing optoelectronic attributes including a high absorption coefficient, a controllable band gap, a long carrier lifetime, and high carrier mobility. [1][2][3][4] The last decade has witnessed unprecedented progress of perovskite solar cells (PSCs) owing to the remarkable properties of organic-inorganic hybrid perovskite materials, with power-conversion efficiency (PCE) reaching up to 26.1%, 5 on par with that of crystalline silicon solar cells. Nonetheless, the intrinsic defects of PSCs and the composition of their multilayered structure give rise to carrier recombination and ion migration, posing a serious challenge to the efficiency and stability of devices.…”