Efficient green light-emitting diodes based on quasi-two-dimensional composition and phase engineered perovskite with surface passivation

Abstract

Perovskite light-emitting diodes (LEDs) are attracting great attention due to their efficient and narrow emission. Quasi-two-dimensional perovskites with Ruddlesden–Popper-type layered structures can enlarge exciton binding energy and confine charge carriers and are considered good candidate materials for efficient LEDs. However, these materials usually contain a mixture of phases and the phase impurity could cause low emission efficiency. In addition, converting three-dimensional into quasi-two-dimensional perovskite introduces more defects on the surface or at the grain boundaries due to the reduction of crystal sizes. Both factors limit the emission efficiency of LEDs. Here, firstly, through composition and phase engineering, optimal quasi-two-dimensional perovskites are selected. Secondly, surface passivation is carried out by coating organic small molecule trioctylphosphine oxide on the perovskite thin film surface. Accordingly, green LEDs based on quasi-two-dimensional perovskite reach a current efficiency of 62.4 cd A−1 and external quantum efficiency of 14.36%.

Probing molecule-like isolated octahedra via phase stabilization of zero-dimensional cesium lead halide nanocrystals

“…Over the past few years, inorganic lead halide perovskites have attracted great attention as a promising optoelectronic material for light-emitting devices, photodetectors, and low-threshold lasers, owing to their high photoluminescence quantum yield (PL QY), narrow emission, and tunable band gap 1–4 . The basic building block in these material is PbX 6 octahedra (where X is a halogen), whose diverse connectivity can produce structures with various dimensionalities, ranging from three-dimensional (3D) to zero-dimensional (0D) 5–7 .…”

Two-dimensional organic-inorganic hybrid perovskite: from material properties to device applications

“…By far the EQEs of 2D perovskite LED have exceeded those of 3D ones in red and green colours [12,106]. However, the performances of blue 2D perovskite still remain moderate [81].…”

“…Furthermore, the 2D perovskite has good filmforming properties compared with 3D analogue [12,55]. These excellent exciton and film-forming properties of 2D perovskite bring about an enhanced PLQE and remarkable EQE of 14.36% [106]. Particularly, although the pure-2D 2D-perovskites have good film-forming properties (like in quasi-2D ones) [107], the excitons in them quench rapidly regarding nonradiative recombination, resulting in low PLQEs [59,108].…”

Control of Interface Defects for Efficient and Stable Quasi‐2D Perovskite Light‐Emitting Diodes Using Nickel Oxide Hole Injection Layer

“…Metal halide perovskites (MHPs) have emerged as a promising class of materials for optically pumped lasers and light‐emitting diodes (LEDs) owing to their narrow emission spectrum and wide range of color tunability 1, 2, 3, 4, 5, 6, 7. To date, perovskite LEDs (PeLEDs) have recorded an external quantum efficiency (EQE) of up to 14.36% for green emissions6 and 12.7% for near‐infrared emissions 7.…”

“…To date, perovskite LEDs (PeLEDs) have recorded an external quantum efficiency (EQE) of up to 14.36% for green emissions6 and 12.7% for near‐infrared emissions 7. However, the low exciton binding energy in MHPs is a fundamental limitation that leads to the generation of free charges at room temperature.…”