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Polycrystalline perovskite light-emitting diodes (PeLEDs) have shown great promise with high efficiency and easy processability. However, PeLEDs using single-cation polycrystalline perovskite emitters have demonstrated low efficiency due to defects within the grains and at the interfaces between the perovskite layer and the charge injection contact. Thus, simultaneous defect engineering of perovskites to suppress exciton loss within the grains and at the interfaces is crucial for achieving high efficiency in PeLEDs. Here, 1,8-octanedithiol which is a strong nucleophile, is used to increase the luminescence efficiency of a single-cation perovskite by suppressing non-radiative recombination within the grains of their polycrystalline emitter film as well as at their interface with an anode. The dithiol additive performs a multifunctional role in defect passivation, spatial confinement of excitons, and prevention of exciton quenching at the interface between the perovskite layer and the underlying hole-injection layer. Photoluminescence studies demonstrate that incorporating the dithiol additive significantly enhances the charge carrier dynamics in perovskites, resulting in an external quantum efficiency (EQE) of up to 23.46% even in a simplified PeLED that does not use a hole-injection layer. This represents the highest level of EQE achieved among devices utilizing polycrystalline single-cation perovskites., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Hole-transporting materials (HTMs) based on the 10H, 10'H-9,9'-spirobi [acridine] core (BSA50 and BSA51) were synthesized, and their electronic properties were explored. Experimental and theoretical studies show that the presence of rigid 3,6-dimethoxy-9H-carbazole moieties in BSA 50 brings about improved hole mobility and higher work function compared to bis(4-methoxyphenyl)amine units in BSA51, which increase interfacial hole transportation from perovskite to HTM. As a result, perovskite solar cells (PSCs) based on BSA50 boost power conversion efficiency (PCE) to 22.65 %, and a PSC module using BSA50 HTM exhibits a PCE of 21.35 % (6.5×7 cm) with a V oc of 8.761 V and FF of 79.1 %. The unencapsulated PSCs exhibit superior stability to devices employing spiro-OMeTAD, retaining nearly 90 % of their initial efficiency after 1000 h operation output. This work demonstrates the high potential of molecularly engineered spirobi[acridine] derivatives as HTMs as replacements for spiro-OMeTAD., (© 2022 Wiley-VCH GmbH.)

Despite organic/inorganic lead halide perovskite solar cells becoming one of the most promising next-generation photovoltaic materials, instability under heat and light soaking remains unsolved. In this work, a highly hydrophobic cation, perfluorobenzylammonium iodide (5FBzAI), is designed and a 2D perovskite with reinforced intermolecular interactions is engineered, providing improved passivation at the interface that reduces charge recombination and enhances cell stability compared with benchmark 2D systems. Motivated by the strong halogen bond interaction, (5FBzAI) 2 PbI 4 used as a capping layer aligns in in-plane crystal orientation, inducing a reproducible increase of ≈60 mV in the V oc , a twofold improvement compared with its analogous monofluorinated phenylethylammonium iodide (PEAI) recently reported. This endows the system with high power conversion efficiency of 21.65% and extended operational stability after 1100 h of continuous illumination, outlining directions for future work., Competing Interests: The authors declare no conflict of interest., (© 2020 The Authors. Published by Wiley‐VCH GmbH.)

This paper reports highly bright and efficient CsPbBr 3 perovskite light-emitting diodes (PeLEDs) fabricated by simple one-step spin-coating of uniform CsPbBr 3 polycrystalline layers on a self-organized buffer hole injection layer and stoichiometry-controlled CsPbBr 3 precursor solutions with an optimized concentration. The PeLEDs have maximum current efficiency of 5.39 cd A -1 and maximum luminance of 13752 cd m -2 . This paper also investigates the origin of current hysteresis, which can be ascribed to migration of Br - anions. Temperature dependence of the electroluminescence (EL) spectrum is measured and the origins of decreased spectrum area, spectral blue-shift, and linewidth broadening are analyzed systematically with the activation energies, and are related with Br - anion migration, thermal dissociation of excitons, thermal expansion, and electron-phonon interaction. This work provides simple ways to improve the efficiency and brightness of all-inorganic polycrystalline PeLEDs and improves understanding of temperature-dependent ion migration and EL properties in inorganic PeLEDs., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Highly efficient organic/inorganic hybrid perovskite light-emitting diodes (PeLEDs) based on graphene anode are developed for the first time. Chemically inert graphene avoids quenching of excitons by diffused metal atom species from indium tin oxide. The flexible PeLEDs with graphene anode on plastic substrate show good bending stability; they provide an alternative and reliable flexible electrode for highly efficient flexible PeLEDs., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A versatile metal nanowiring platform enables the fabrication of Ag nanowires (AgNW) at a desired position and orientation in an individually controlled manner. A printed, flexible AgNW has a diameter of 695 nm, a resistivity of 5.7 μΩ cm, and good thermal stability in air. Based on an Ag nanowiring platform, an all-NW transistors array, as well as various optoelectronic applications, are successfully demonstrated., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel flexible encapsulation method (Flex Lami-capsulation) is reported, which can be applied in the roll-to-roll process for mass production of organic electronic devices. Flex Lami-capsulation is very simple, fast, and getter-free, and is as effective as glass encapsulation. Use of this method is feasible in large-area flexible displays and does not have the drawbacks of conventional encapsulation methods., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A self-organized hole extraction layer (SOHEL) with high work function (WF) is designed for energy level alignment with the ionization potential level of CH3 NH3 PbI3 . The SOHEL increases the built-in potential, photocurrent, and power conversion efficiency (PCE) of CH3 NH3 PbI3 perovskite solar cells. Thus, interface engineering of the positive electrode of solution-processed planar heterojunction solar cells using a high-WF SOHEL is a very effective way to achieve high device efficiency (PCE = 11.7% on glass)., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)