Efficient metal halide perovskite light-emitting diodes with significantly improved light extraction on nanophotonic substrates

Abstract

Metal halide perovskite has emerged as a promising material for light-emitting diodes. In the past, the performance of devices has been improved mainly by optimizing the active and charge injection layers. However, the large refractive index difference among different materials limits the overall light extraction. Herein, we fabricate efficient methylammonium lead bromide light-emitting diodes on nanophotonic substrates with an optimal device external quantum efficiency of 17.5% which is around twice of the record for the planar device based on this material system. Furthermore, optical modelling shows that a high light extraction efficiency of 73.6% can be achieved as a result of a two-step light extraction process involving nanodome light couplers and nanowire optical antennas on the nanophotonic substrate. These results suggest that utilization of nanophotonic structures can be an effective approach to achieve high performance perovskite light-emitting diodes.

The role of photon recycling in perovskite light-emitting diodes

“…Here, we assumed that these α values are sufficiently high for re-absorption (and hence PR) to dominate over scattering, at least in the planar devices. Although scattering can in general provide an effective means to extract photons from trapped modes by randomising the propagation angle, we expect it can dominate over PR in some devices having (i) exceptionally rough interfaces or nanostructures; 3,16,25,41 (ii) large Stokes shifts (e.g., emitters mixed with host materials); or (iii) low radiation efficiency (e.g., solar cells). The study of devices where both PR and scattering are important will be an important goal for future research.…”

Role of Excess FAI in Formation of High‐Efficiency FAPbI3‐Based Light‐Emitting Diodes

“…Atomic force microscope (AFM) characterization shows comparable thickness for perovskite films x = 0 and x = 90 (Figure S3, Supporting Information), by which we can exclude the influence of film thickness on device performance. Notably, recent studies suggest that a discrete morphology of the perovskite emissive layer is beneficial for light extraction and thus improves the EQE of the perovskite LED devices . It is noteworthy that the island structure of the x = 90 sample may lead to better light out‐coupling as compared to the plane structure of the x = 0 sample; however, previous studies suggest that such light extraction‐related EQE improvement by film morphology or thickness optimization is limited (usually below two times).…”

Tunable self‐powered n‐SrTiO3 photodetectors based on varying CuS‐ZnS nanocomposite film (p‐CuZnS, p‐CuS, and n‐ZnS)

“…Photodetectors, which detect irradiation directly by transforming light into electrical signals based on photoelectric effect, have been extensively used in various applications, such as environmental monitoring, biological/chemical analysis, flame detection, and communications . Recently, many groups are dedicated to realizing photodetectors with self‐powered characteristics .…”

“…Photodetectors, which detect irradiation directly by transforming light into electrical signals based on photoelectric effect, have been extensively used in various applications, such as environmental monitoring, biological/chemical analysis, flame detection, and communications. [1][2][3][4][5][6][7] Recently, many groups are dedicated to realizing photodetectors with self-powered characteristics. [8][9][10][11][12] The self-powered devices can work under zero bias due to the photovoltaic effect from p-n junctions or heterojunctions under light illumination, and are particularly appealing for their miniaturization and portability.…”