Scalable All‐Evaporation Fabrication of Efficient Light‐Emitting Diodes with Hybrid 2D–3D Perovskite Nanostructures

Abstract

Quasi-2D (Q2D) lead halide perovskites have emerged as promising materials for light-emitting diodes (LEDs) due to their tunable emission, sloweddown carrier diffusion, and improved stability. However, they are primarily fabricated through solution methods, which hinders its large-scale manufacture and practical applications. Physical-vapor-deposition (PVD) methods have well demonstrated the capability for reproducible, scalable, and layerby-layer fabrication of high quality organic/inorganic thin films. Herein, for the first time, the full-evaporation fabrication of organic-inorganic hybrid ((BA) 2 Cs n−1 Pb n Br 3n+1) Q2D-3D PeLEDs is demonstrated. The morphology and crystal phase of the perovskite are controlled from 3D to 2D by modulating material composition, annealing temperature, and film thicknesses. The confinement of carriers in 3D layers and the energy funnel effect are discovered and discussed. Importantly, a record high external quantum efficiency (EQE) of 5.3% based on evaporation method is achieved. Moreover, a centimeterscale PeLED (1.5 cm × 2 cm) is obtained. Furthermore, the T 50 lifetime of the device with an initial brightness of 100 cd m −2 is found to be 90 min with a thin layer PMMA passivation, which is among the longest for all PVD processed PeLEDs. Overall, this work casts a solid stepping stone towards the fabrication of high-performance PeLEDs on a large-scale.

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

“…Meanwhile, by depositing butylammonium bromide on top of thermally evaporated CsPbBr 3 perovskites, the resultant surface morphology can considerably vary after thermal annealing at a moderate temperature. [153] Regarding the CsPbBr 3 and CsPbBrCl 2 , the welldefined micron-hemisphere structures can be achieved on the silicon substrates by chemical vapor deposition via the precise control of processing parameters, showing extraordinary lasing characters based on the cavity effect. [154] In contrast to vapor-phase perovskites, the microstructural morphology of solution-processed perovskites is typically controlled by varying processing parameters and chemical compositions.…”

Vacuum‐Processed Metal Halide Perovskite Light‐Emitting Diodes: Prospects and Challenges

“…To date most of the thermally evaporated PeLEDs were prepared from either MAPbX 3 or CsPbX 3 compositions, however, there is a dearth of work done on FAPbX 3 perovskite constituents. It has been noticed that quasi‐2D perovskites and passivation effect on perovskite thin‐films significantly improve the device performance [42,43,56,62] . In quasi‐2D perovskites, the inorganic PbX 2 layers usually act as a quantum well and the organic layers behave as a barrier.…”

“…While the LiBr passivated PeLEDs exhibited a maximum luminescence of 13,380 Cd/m 2 with an EQE of 1.42 %, and nearly three times improvement of device performance was observed. Quasi‐2D perovskite (BA) 2 Cs n−1 Pb n Br 3n+1 ) thin‐films‐based PeLEDs performed better due to their quantum well structure which improves the radiative recombination [62] . The PeLEDs were fabricated with a device structure of ITO/CuPc (20 nm)/Perovskite (200 nm)/TPBi (50 nm)/LiF (3 nm)/ Ag (100 nm).…”

The Past, Present, and Future of Metal Halide Perovskite Light‐Emitting Diodes

“…[ 146 ] Following that, PeLEDs fabricated by vapor deposition were reported by many research groups (Figure 9d). [ 147–150 ] However, the device performance of vapor‐deposited PeLEDs reported to date lags far behind those of hybrid‐processed PeLEDs, where MHP layers are prepared via solution processing and CTLs are prepared by either solution processing or vapor deposition. As vapor deposition often forms polycrystalline MHP thin films, it is challenging to realize high exciton binding energies and PLQEs.…”