Perovskite-based optoelectronic devices have gained significant attention due to their remarkable performance and low processing cost, particularly for solar cells. However, for perovskite light-emitting diodes (LEDs), non-radiative charge carrier recombination has limited electroluminescence (EL) efficiency. Here we demonstrate perovskite-polymer bulk heterostructure LEDs exhibiting record-high external quantum efficiencies (EQEs) exceeding 20%, and an EL half-life of 46 hours under continuous operation. This performance is achieved with an emissive layer comprising quasi-2D and 3D perovskites and an insulating polymer. Transient optical spectroscopy reveals that photogenerated excitations at the quasi-2D perovskite component migrate to lower-energy sites within 1 ps. The dominant component of the photoluminescence (PL) is primarily bimolecular and is characteristic of the 3D regions. From PL quantum efficiency and transient kinetics of the emissive layer with/without charge-transport contacts, we find non-radiative recombination pathways to be effectively eliminated. Light outcoupling from planar LEDs, as used in OLED displays, generally limits EQE to 20-30%, and we model our reported EL efficiency of over 20% in the forward direction to indicate the internal quantum efficiency (IQE) to be close to 100%. Together with the low drive voltages needed to achieve useful photon fluxes (2-3 V for 0.1-1 mA cm -2 ), these results establish that perovskite-based LEDs have significant potential for light-emission applications.

The Clouds and the Earth’s Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) top-of-atmosphere (TOA), Edition 4.0 (Ed4.0), data product is described. EBAF Ed4.0 is an update to EBAF Ed2.8, incorporating all of the Ed4.0 suite of CERES data product algorithm improvements and consistent input datasets throughout the record. A one-time adjustment to shortwave (SW) and longwave (LW) TOA fluxes is made to ensure that global mean net TOA flux for July 2005–June 2015 is consistent with the in situ value of 0.71 W m−2. While global mean all-sky TOA flux differences between Ed4.0 and Ed2.8 are within 0.5 W m−2, appreciable SW regional differences occur over marine stratocumulus and snow/sea ice regions. Marked regional differences in SW clear-sky TOA flux occur in polar regions and dust areas over ocean. Clear-sky LW TOA fluxes in EBAF Ed4.0 exceed Ed2.8 in regions of persistent high cloud cover. Owing to substantial differences in global mean clear-sky TOA fluxes, the net cloud radiative effect in EBAF Ed4.0 is −18 W m−2 compared to −21 W m−2 in EBAF Ed2.8. The overall uncertainty in 1° × 1° latitude–longitude regional monthly all-sky TOA flux is estimated to be 3 W m−2 [one standard deviation (1 σ)] for the Terra-only period and 2.5 W m−2 for the Terra– Aqua period both for SW and LW fluxes. The SW clear-sky regional monthly flux uncertainty is estimated to be 6 W m−2 for the Terra-only period and 5 W m−2 for the Terra– Aqua period. The LW clear-sky regional monthly flux uncertainty is 5 W m−2 for Terra only and 4.5 W m−2 for Terra– Aqua.

meantime, the ease of the solution process at low temperature renders this technology up-and-coming for large-scale low-cost manufacture. However, these solution-processed perovskite films are usually polycrystalline, which readily form defects at the grain boundaries and on the surface of the films. [1][2][3][4][5][6] Such defects are the center of non-radiative recombination of photo-generated electrons and holes, which causes shorter carrier lifetime and lower open-circuit voltage (V OC ). Hence, in real devices, higher recombination rate occurs close to the interface of the sequentially deposited layers. For typical n-i-p perovskite solar cells (PSCs), the perovskite/hole transport layer (HTL) interface holds the high defect density, such as cation/anion vacancy and dangling bonds, etc., [7,8] resulting in defect-assisted recombination. Additionally, the energy level mis-alignment near the interface due to quasi-fermi level pinning will increase recombination velocity [9] and the recombination loss occurs inevitably across interfaces between holes in HTL and minority carriers (electron) in the perovskite, or HTL themselves. [10,11] These existing recombination loss channels at the surface/ interface of the perovskite will severely limit the V OC and overall efficiency of PSCs.Many studies have demonstrated that passivation is an efficient method to lessen the non-radiative recombination loss at the surface/interface of the perovskite in n-i-p PSCs. For example, excess PbI 2 [4,[12][13][14] was believed to passivate the grain boundaries and interface of electron transport layer with perovskite; conjugated polymers [15] and insulating poly(methyl methacrylate) [16,17] were also used to passivate the interface of perovskite/HTL. Recently, various ammonium halide compounds, [8,18,19] especially bulky organic ammonium halide salts were adopted to passivate the surface of perovskite, such as 1,8-octanediammonium iodide, [3] adamantylammonium hydroiodide, [7] (fluorine-)phenylethylammonium iodide (F-)PEAI, [20][21][22][23] n-hexyl trimethyl ammonium bromide, [24] etc. They could interact with the undercoordinated ions or form low-dimensional perovskite phases to passivate the surface/ interface of bulk perovskite. The stability of devices was also usually improved due to the suppression of ionic migration by the packed organic moiety or the formation of hydrophobic low-dimensional perovskites. [7,23,25] A very recent work by Jiang et al. found exceptionally that the insulating PEAI salt, rather than the 2D layered PEA 2 PbI 4 perovskite, served as a moreThe presence of non-radiative recombination at the perovskite surface/ interface limits the overall efficiency of perovskite solar cells (PSCs). Surface passivation has been demonstrated as an efficient strategy to suppress such recombination in Si cells. Here, 1-naphthylmethylamine iodide (NMAI) is judiciously selected to passivate the surface of the perovskite film. In contrast to the popular phenylethylammonium iodide, NMAI post-treatment primarily leaves NMAI sal...