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Hot‐injection methods are widely used for the synthesis of colloidal perovskite nanocrystals (PeNCs). However, the long‐chain hydrocarbon solvents with alkene groups, such as octadecene (ODE), cannot be removed completely due to the strong van der Waals force between ODE and surface ligands as well as the large difference in the polarity with ethyl acetate, which hinders the charge transport characteristic of PeNCs and thus reduces the performance of PeNC‐based light‐emitting diodes (PeLEDs). Herein, an alkene‐free solvent‐assisted strategy is reported to synthesize high‐quality CsPbBr3 PeNCs in toluene and it is found that the alkene‐free solvent can significantly influence the morphology, composition, and optoelectronic properties of PeNCs. Compared to the traditional ODE solvent with alkene groups, toluene endows the higher solubility of precursors, which reduces the growth rate of PeNCs and allows sufficient time for the perovskite crystallization to suppress the bulk defects. Moreover, the similar polarity between toluene and ethyl acetate avoids long‐chain solvent residual on the PeNCs, thereby improving the charge transport characteristics. Making use of these PeNCs prepared with toluene solvent, the resulting PeLEDs present a peak external quantum efficiency of over 15%, 1.5‐fold higher than that of the device based on PeNCs that are prepared in ODE. [ABSTRACT FROM AUTHOR]

1D metal halide perovskites (MHPs) are known as excellent candidates for fabricating high‐performance optoelectronic devices, ranging from lasers to photodetectors (PDs). Nevertheless, their inherent limitations, such as high binding energy and limited carrier mobility, have restricted their further improvement in performance. To tackle this issue, hybrid MHP microwires (MWs) are fabricated by combining MHP MWs and an organic semiconductor via a facile self‐assembly method, forming a radial heterojunction. Meanwhile, an ultrathin insulating organic layer is introduced as an interlayer between MHP MWs and the organic semiconductor. The synthesized hybrid MWs are further applied in rigid and flexible PDs, which demonstrated a high light/dark current on‐off ratio (>2 × 105), a high responsivity (>400 A W−1), and robust bending stability. These impressive results make the hybrid MHP MWs with the unique radial heterostructure promising building blocks for high‐performance future optoelectronics. [ABSTRACT FROM AUTHOR]

Polarization emission from halide perovskite is expected to bring a lot of benefits for next‐generation displays, such as cost down, wide color gamut, and structure simplification. In this work, strong linearly polarized luminescence from emissive halide perovskites modulated by photoaligned azobenzene dye AD1 is demonstrated. The azobenzene dye functionalized halide perovskite thin films not only exhibit exceptionally high degree of polarization (DOP) of 86.2–93.1% for red, green, and blue emission, but also promise an improved environmental stability originating from the hydrophobic nature of the azobenzene dye. When these perovskite/AD1 composite films are applied in liquid crystal display panels to replace the conventional thick polarizer, the energy efficiency can be doubled and the color gamut can be extended to >120% NTSC. Furthermore, the AD1 functionalized strategy is successfully employed to generate linearly polarized electroluminescence from an inverted perovskite light‐emitting diode, showing a high DOP of 47%. [ABSTRACT FROM AUTHOR]

Metal halide perovskites have attracted considerable attention in the field of light‐emitting diodes due to their high color purity and solution processability. However, most perovskite light‐emitting diodes (PeLEDs) employ thermally deposited charge transport layers (CTLs) on top of perovskite layers. In order to realize low‐cost and scalable fabrication of PeLEDs, all‐solution process is highly desired, but still remaining great challenges. Here, an efficient all‐solution‐processed green PeLEDs is reported by incorporating 1,3,5‐tris(1‐phenyl‐1H‐benzimidazol‐2‐yl)benzene (TPBi) doped conjugated amino‐alkyl substituted polyfluorene poly[(9,9‐bis(3′‐(N,N‐dimethylamino)propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)] (PFN) electron injection layer, achieving a maximum luminance of 9875 cd m−2, a high current efficiency of 10.41 cd A−1, and an external quantum efficiency of 3.19%. Since the solvents used for perovskite precursors and PFN are orthogonal, the protected and complete interface of perovskite film and CTL is effectively obtained by solution processes. The doping of TPBi into PFN not only enhances the capability of electron injection, but also significantly suppresses the emission quenching of perovskite films caused by the charge transfer between perovskite and PFN due to the reduced difference in their work functions. This work provides an efficient approach for the development of all‐solution‐processed PeLEDs. [ABSTRACT FROM AUTHOR]