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The realization of highly operationally stable blue organic light‐emitting diodes (OLEDs) is a challenge in both academia and industry. This paper describes the development of anthracene–dibenzofuran host materials, 2‐(10‐(naphthalen‐1‐yl)anthracen‐9‐yl)naphtho[2,3‐b]benzofuran (Host 1) and 2‐(10‐([1,1′‐biphenyl]‐2‐yl)anthracen‐9‐yl)naphtho[2,3‐b]benzofuran (Host 2), namely for use in the emissive layer of an OLED stack. A multiple‐resonance thermally activated delayed serves as the blue fluorescence emitter and exhibits an initial luminance of 1000 cd m−2 and long operational stability (i.e., time to decay to 90% of initial luminance) of 249 h. Furthermore, a deep‐blue OLED with an optimized top‐emitting architecture with a high current efficiency of 154.3 cd A−1, is fabricated and calibrated to a Commission International de l'Éclairage y chromaticity coordinate of 0.048. Moreover, the emission spectrum of this OLED has a narrowband peak at 476 nm with a full width at half maximum (FWHM) of 16 nm. This work provides valuable insights into the design of anthracene‐based host materials and highlights the importance of host optimization in improving the operational stability of OLEDs. [ABSTRACT FROM AUTHOR]

Despite the ongoing breakthroughs in power conversion efficiency (PCE) of perovskite solar cells (PSCs), the presence of inherent defects in perovskite films remains the predominant hurdle impeding the further progress of this promising photovoltaic technology. Herein, we propose a straightforward yet highly effective additive strategy to passivate the bulk defects of perovskite films. Specifically, based on the two-step deposition method, a functional polymer poly(2-ethyl-2-oxazoline) (PEOXA) was introduced into the PbI2 precursor solution, facilitating the formation of the PbI2-dimethyl sulfoxide phase. This solvate facilitates subsequent intercalation reactions with organic cations, resulting in the formation of high-quality perovskite films. Additionally, due to its abundant active sites and larger molecular size, PEOXA forms a three-dimensional network structure at the perovskite grain boundaries, effectively connecting the grains and suppressing ion migration. The C = O groups in PEOXA passivate the uncoordinated Pb2+ defects at the grain boundaries, inhibiting non-radiative charge recombination in the bulk. As a result, the device PCE increased from 22.02% to 24.27%. Furthermore, the PEOXA-based PSCs exhibited excellent operational stability, retaining 86% of the initial efficiency after continuous operation for 1500 h. [ABSTRACT FROM AUTHOR]

Lead‐halide perovskite materials have emerged as promising alternatives for optoelectronic applications due to their low‐cost, easily tunable bandgaps, and facile solution‐processability. Despite all their exciting merits, perovskite materials are currently suffering the stability issues, such as moisture and oxygen‐induced rapid degradation and phase transition. In this work, γ phase CsPbI3 perovskite thin films with compact grain boundaries and improved ambient stability are successfully developed via introducing poly‐2‐ethyl‐2‐oxazoline (PEOXA) polymer through an effective bonding between CO double bond in PEOXA with perovskite. The optimized photodetectors with the γ‐CsPbI3:5%PEOXA active thickness as thin as 30 nm have a totally excellent performance with a responsivity of 0.16 A W−1, high detectivity of 2.73 × 1012 Jones, linear dynamic range of over 125 dB, and ultrafast rise/decay time of 13.9/12.7 µs. Moreover, the as‐constructed photodetectors have shown a high stability when maintained under ambient conditions. This work provides new insights for the development of highly stable and efficient perovskite‐based optoelectronics. [ABSTRACT FROM AUTHOR]

Despite the rapid advancement in electroluminescence efficiencies of perovskite light‐emitting diodes (PeLEDs), it remains challenging to achieve efficient and reproducible devices. Herein, an effective vapor‐assisted growth (VAG) method is proposed to develop quasi‐2D perovskite thin‐films via creating a saturated dimethyl sulfoxide vapor environment. The VAG‐optimized perovskite films with a composition of PEA2(FAPbBr3)n−1PbBr4 display uniformly distributed nanograins with graded energy landscape and compact surface, contributing to enhanced radiative and suppressed nonradiative recombination. Consequently, the PeLEDs incorporating VAG‐based films with a device architecture of indium tin oxide/poly(9,9‐dioctylfluorene‐alt‐N‐(4‐sec‐butylphenyl)‐diphenylamine)/perovskite/(1,3,5‐tris(phenyl‐2‐benzimidazolyl)benzene)/Yb/Ag demonstrate a peak current efficiency of 27.1 cd A−1 (@ 532 nm) with an external quantum efficiency of 6.50% and a maximum luminance of 17 610 cd m−2. Notably, champion PeLEDs manifest considerably curtailed efficiency roll‐off as ≈50% of the peak efficiency is preserved even at a very high luminance of 15 000 cd m−2. Meanwhile, VAG‐based PeLEDs exhibit improved reproducibility compared to the control counterparts. It is anticipated that this work would promote the development of reliable solution‐processing methods toward stabilized perovskite‐based photonics. [ABSTRACT FROM AUTHOR]

Remarkable progress has been achieved in perovskite light‐emitting diodes (PeLEDs). Both green and infrared PeLEDs with external quantum efficiencies (EQEs) of over 20% are successfully developed. However, the performance of pure red PeLEDs remains challenging. Numerous efforts are explored to tune red color emission for higher emission efficiencies, but it is still suffering operation instability. Here, high‐quality and luminescent quasi‐2D (CsPbBrxI3−x)/poly(2‐ethyl‐2‐oxazoline) (PEOXA) composite perovskite thin films are successfully fabricated via a one‐step method. Uniform and smooth perovskite thin films are obtained with photoluminescent quantum yield as high as 65% and emission is tuned from pure red to deep red (638–686 nm). Efficient PeLEDs with device structure of indium tin oxide/ZnMgO/quasi‐2D perovskite/Poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)‐benzidine] (Poly‐TPD)/MoO3/Ag have demonstrated a high EQE of 7.0% and pure red emission peak at 654 nm, with Commission Internationale de l'Éclairage coordinates of (0.703, 0.287). While the PeLEDs with an emission peak at 670 nm show a low turn‐on voltage of 1.6 V, maximum luminance of 1942 cd m−2, and maximum EQE of 9.1%. In addition, the PeLEDs achieve good spectral and operational stability with a record half‐lifetime (T50) of over 20 h at a high initial luminance of 100 cd m−2, demonstrating their good potential for display application. [ABSTRACT FROM AUTHOR]

Because of their high efficiency and sharp emission, perovskite light-emitting diodes are a promising candidate for next-generation lighting techniques. However, the relatively poor stability of perovskite light-emitting diodes lowers their utility. Therefore, a highly stable perovskite light-emitting diode has to be developed to meet the commercial demand. Herein, we report a highly stable CsPbBr 3 light-emitting diode via simple polymer treatment. The addition of 2-methyl-2-oxazoline in perovskite film assists the formation of CsPbBr 3 nanocrystals, improving the quality and photoluminescence property of perovskite film. Based on such CsPbBr 3 nanocrystals and polymer hybrid film, our device presents a high external quantum efficiency and luminance of around 3.0% and 16 648 cd m -2 , respectively. Moreover, an excellent device half-lifetime of more than 2.4 hours has been achieved, under continuous operation at a relatively high initial luminance of 1000 cd m -2 , representing one of the most stable PeLEDs operated at such high initial luminance., Competing Interests: The authors declare that they have no conflict of interest., (This journal is © The Royal Society of Chemistry.)