Minimizing Optical Energy Losses for Long‐Lifetime Perovskite Light‐Emitting Diodes

Abstract

Regardless of the rapid advance on perovskite light‐emitting diodes (PeLEDs), the lack of long‐term operational stability hinders the practicality of this technology. Particularly, thermal management is indispensable to control the Joule heating induced by charge transport and parasitic re‐absorption of internally confined photons. Herein, a synergetic device architecture is proposed for minimizing the optical energy losses in PeLEDs toward high efficiency and long lifetime. By adopting a carefully modified perovskite emitter in combination with an improved light outcoupling structure, red PeLEDs emitting at 666 nm achieve a peak external quantum efficiency of 21.2% and an operational half‐lifetime of 4806.7 h for an initial luminance of 100 cd m‐2. The enhanced light extraction from trapped modes can efficiently reduce the driving current and suppress optical energy losses in PeLEDs, which in turn ameliorate the heat‐induced device degradation during operation. This work paves the way toward high‐performance PeLEDs for display and lighting applications in the future.

Ion Migration in Perovskite Light‐Emitting Diodes: Mechanism, Characterizations, and Material and Device Engineering

“…A patterned device with lower operation current density could also reduce Joule heating and decrease the operation temperature, resulting in a T 50 of 4806.7 h at 100 cd m −2 . [261] Moreover, the working temperature of quasi-2D PeLEDs was decreased from 36.3 to 29.6 °C (Figure 12a) by introducing p-fluorophenethylammonium (p-PEA + ), which was ascribed to the suppressed Auger recombination. [262] Thinner emitting films can also facilitate heat dissipation and reduce the junction temperature to enhance durability of working PeLEDs (Figure 12b).…”

Metal Halide Perovskites for Red‐Emission Light‐Emitting Diodes

“…[ 141 ] Recently, Tang et al used soft nanoimprinting to pattern the functional layers and constructed nanocellular arrays and nanocone arrays to build light outcoupling structure, which can restrict light in waveguide and substrate modes. [ 142 ] As a result, they increased the efficiency of PeLEDs from 10.1% to 21.2%, and prolonged lifetime up to 4806.7 h @ 100 cd m −2 .…”

“…This process creates a vicious circle resulting in irreversible phase separation and decomposition. [ 142 ] To figure out the Joule heating issue during device's long‐term operation, several perspectives need to be considered, including reducing current density, balancing charge injection to reduce resistance, and enhancing thermal management. Thermal management strategies include external adsorption heat sinks, [ 143 ] balanced charge injection, and optimizing light extraction structures to inhibit light reabsorption.…”

Strategies to Improve the Stability of Perovskite Light-Emitting Diodes: Progress and Perspective

“…As illustrated in Figure 5d, Tang et al introduced nanostructures with quasi-periodic nanostructures inside the PeLEDs and onto the outer surface of the glass substrate by a soft nanoimprinting method. 55 This synergistic optical structure could effectively release the light trapped in the waveguide and substrate modes, contributing to higher light-outcoupling efficiency and suppressed heat accumulation. By applying this strategy, a high T 50 of luminance at constant current density was estimated to be 4806 h for red PeLEDs with a peak EQE over 20%.…”

“…The effectiveness of promoting better heat dissipation by using sapphire for improved operational stability of PeLEDs has also been confirmed by Lin et al In addition, patterning the perovskite films with finely designed nanostructures has also been demonstrated to improve optical outcoupling and favorable thermal management. As illustrated in Figure d, Tang et al introduced nanostructures with quasi-periodic nanostructures inside the PeLEDs and onto the outer surface of the glass substrate by a soft nanoimprinting method . This synergistic optical structure could effectively release the light trapped in the waveguide and substrate modes, contributing to higher light-outcoupling efficiency and suppressed heat accumulation.…”