Metal halide-based perovskites are regarded as promising candidates for light-emitting diodes (LEDs) owing to their high color purity, tunable bandgap and solution processability.

Modern lighting requires high efficiency and long lifetime simultaneously. In this paper, highly efficient white organic light emitting diodes (WOLEDs) are demonstrated based on a modified hybrid tandem structure constructed with a phosphorescent yellow‐red unit using an exciplex host and a blue‐red unit based on a thermally activated delayed fluorescence (TADF) blue emitter, and the devices are properly built with internal and external light extraction structures. The resulting four‐color WOLED exhibits an external quantum efficiency and luminous efficacy of 126.2% and 150.7 Lm W−1, respectively, and the color rendering index is close to 80 at a brightness of 1000 cd m−2. This device also shows a very good color stability with increasing luminance up to 15 000 cd m−2 and there is only a small angular color variation for viewing angles changing from 0° to 70°. The T50 lifetime (defined as the time corresponding to 50% decrease in luminance from an initial value) of the WOLED at an initial luminance of 1000 cd m−2 is extrapolated as 12 600 h.

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A uniform and flat CsPbBr3 film with more stable and excellent fluorescence properties in ambient air was achieved by adding lecithin (LE) into CsPbBr3 precursor solution. Moreover, the CsPbBr3–LE film showed outstanding performance in perovskite light-emitting diodes.

Two novel donor−σ–π–σ–acceptor-type dispiro molecules10-phenyl-10H-dispiro-acridine-9,9′-anthracene-10′,9′′-fluorene-2′′,7′′-dicarbo-nitrile (DiSAAF) and dispiro-fluorene-9,9′-anthracene-10′,9′′-quinolino­[3,2,1-kl]­phenoxazine-2,7-dicarbonitrile (DiSFAQ)with excellent thermal stability are designed and synthesized. Both materials exhibit blocked long-range intramolecular charge transfer but show intermolecular charge-transfer emission in the film state. Their photophysical and thermal properties then are fully investigated and a maximum external quantum efficiency of 21.7% of the red phosphorescent device is achieved by DiSAAF.

Monolithic perovskite/organic tandem solar cells (POTSCs) have significant advantages in next‐generation flexible photovoltaics, owing to their capability to overcome the Shockley–Queisser limit and facile device integration. However, the compromised sub‐cells performance challenges the fabrication of high‐efficiency POTSCs. Especially for all‐inorganic wide‐bandgap perovskite front sub‐cells (AIWPSCs) based n‐i‐p structured POTSCs (AIPOTSCs), for which the power conversion efficiency (PCE) is much lower than organic–inorganic mixed‐halide wide‐bandgap perovskite based POTSCs. Herein, an ionic liquid, methylammonium formate (MAFm), based dual‐interface engineering approach is developed to modify the bottom and top interfaces of wide‐bandgap CsPbI2Br films. In particular, the Fm− group of MAFm can effectively passivate the interface defects, and the top interface modification can facilitate the formation of uniform perovskite films with enlarged grain size, thereby mitigating the defects and perovskite grain boundaries induced carrier recombination. As a result, CsPbI2Br‐based AIWPSCs with a high PCE of 17.0% and open‐circuit voltage (VOC) of 1.347 V are achieved. By integrating these dual‐interface engineered CsPbI2Br‐based front sub‐cells with the narrow‐bandgap PM6:CH1007‐based rear sub‐cells, a record PCE of 23.21% is obtained for AIPOTSCs, illustrating the potential of AIPOTSCs for achieving high‐efficiency tandem solar cells.

Functional passivators are conventionally utilized in modifying the crystallization properties of perovskites to minimize the non‐radiative recombination losses in perovskite light‐emitting diodes (PeLEDs). However, the weak anchor ability of some commonly adopted molecules has limited passivation ability to perovskites and even may desorb from the passivated defects in a short period of time, which bring about plenty of challenges for further development of high‐performance PeLEDs. Here, a multidentate molecule, formamidine sulfinic acid (FSA), is introduced as a novel passivator to perovskites. FSA has multifunctional groups (S≐O, C≐N and NH2) where the S≐O and C≐N groups enable coordination with the lead ions and the NH2 interacts with the bromide ions, thus providing the most effective chemical passivation for defects and in turn the formation of highly stable perovskite emitters. Moreover, the interaction between the FSA and octahedral [PbBr6]4− can inhibit the formation of unfavorable low‐n domains to further minimize the inefficient energy transfer inside the perovskite emitters. Therefore, the FSA passivated green‐emitting PeLED exhibits a high external quantum efficiency (EQE) of 26.5% with fourfold enhancement in operating lifetime as compared to the control device, consolidating that the multidentate molecule is a promising strategy to effectively and sustainably passivate the perovskites.

Energy matching between the triplet level of the exciplex hosts and phosphorescent emitters is of particular importance to achieve highly efficient exciplex-based white organic light emitting diodes (WOLEDs). Herein, we...