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Se‐functionalized small molecule acceptors (SMAs) exhibit unique advantages in constructing materials with near‐infrared absorption, but their photovoltaic performance lags behind that of S‐containing analogs in organic solar cells (OSCs). Herein, two new Se‐containing SMAs, namely Se‐EH and Se‐EHp, are designed and synthesized by regulating bifurcation site of outer alkyl chain, which enables Se‐EH and Se‐EHp to form different 3D crystal frameworks from CH1007. Se‐EH displays tighter π–π stacking and denser packing framework with smaller‐sized pore structure induced by larger steric hindrance effect of outer alkyl chain branched at 2‐position, and a higher dielectric constant of PM6:Se‐EH active layer can be obtained. OSCs based on PM6:Se‐EH achieved very high PCEs of 18.58% in binary and 19.03% in ternary devices with a high FF approaching 80% for Se‐containing SMAs. A more significant alkyl chain steric hindrance effect in Se‐EH adjusts the molecular crystallization to form a favorable nanofiber interpenetrating network with an appropriate domain size to reduce rate of sub‐ns recombination and promote balanced transport of carriers. This work provides references for further design and development of highly efficient Se‐functionalized SMAs. [ABSTRACT FROM AUTHOR]

Due to their unique photoelectric properties, nontoxic tin‐based perovskites are emerging candidates for efficient near‐infrared LEDs. However, the facile oxidation of Sn2+ and the rapid crystallization rate of tin‐based perovskites result in suboptimal film quality, leading to inferior efficiencies of tin‐based perovskite light‐emitting diodes (Pero‐LEDs). In this study, we investigate the influence of commonly used solvents on the quality of the CsSnI3 films. Remarkably, DMSO exhibits a stronger interaction with SnI2, forming a stable intermediate phase of SnI2·3DMSO. This intermediate effectively inhibits the oxidation of Sn2+ and slows down the crystallization rate, bringing in lower defect state density and higher photoluminescence quantum yield of the prepared perovskite films. Consequently, the corresponding Pero‐LEDs achieve a maximum external quantum efficiency (EQE) of 5.6%, among the most efficient near‐infrared Pero‐LEDs. In addition, the device processes ultra‐low efficiency roll‐off and high reproducibility. Our research underscores the crucial role of solvent‐perovskite coordination in determining film quality. These findings offer valuable guidance for screening solvents to prepare highly efficient and stable tin‐based perovskites. [ABSTRACT FROM AUTHOR]

Recently, lead‐free Sn‐based perovskite light‐emitting diodes (PeLEDs) have attracted wide attention due to their near‐infrared emission and environmental friendliness. However, desired Sn2+ is easily oxidized to Sn4+ in the crystallization process, resulting in defects and intrinsically p‐doped properties in the perovskite films. The uncontrollable oxidation affects the charge injection balance and radiative recombination, leading to poor device performance. Herein, a bi‐functional conductive molecular, 2,7‐bis(diphenylphosphoryl)‐9,9′‐spirobifluorene (SPPO13) with two P═O functional groups, is used to interact with perovskite to passivate defects and suppress the oxidation of Sn2+. Moreover, the SPPO13 modification layer inserted between the perovskite emitter and the electron transport layer can regulate the carrier injection and transport, thus promoting the charge balance. As a result, the high‐performance near‐infrared CsSnI3 PeLEDs with a record external quantum efficiency (EQE) of 6.60% and ultra‐low efficiency roll‐off are achieved. The work provides a novel approach to regulate defect passivation and charge transport for efficient Sn‐based PeLEDs. [ABSTRACT FROM AUTHOR]

Metal halide perovskite light‐emitting diodes (Pero‐LEDs) have gained great attention due to their promising applications in lighting and displays. However, in their conventional three‐layered sandwich structure, some undeserved carrier behaviors, such as imbalanced carrier injection, severe carrier loss, and unstable recombination zone, limit the device's performance. Herein, a four‐layered design by inserting a nickel acetate (Ni(OAc)2) interlayer between the emitter and hole‐transport layer(HTL) to manage carrier behavior and improve radiative recombination efficiency is proposed. Specifically, the Ni(OAc)2 interlayer is poorly conductive and can partially block the hole injection, making the hole‐electron injection more balanced. And the Ni(OAc)2 interlayer avoids the direct contact between the perovskite emitter and hole transporter, reducing the interfacial carrier quenching. Moreover, the Ni(OAc)2 interlayer inhibits the electron‐migrated recombination at the hole transporter interface, confining the carrier recombination zone in the emitter layer. As a result, the corresponding Pero‐LEDs achieve a maximum external quantum efficiency (EQEmax) of 24.6% with good reproducibility, showing an average EQEmax of over 20%. [ABSTRACT FROM AUTHOR]

Tin‐based perovskite solar cells (TPSCs) have received great attention due to their eco‐friendly properties and high theoretical efficiencies. However, the fast crystallization feature of tin‐based perovskites leads to poor film quality and limits the corresponding device performance. Herein, a chlorofullerene, C60Cl6, with six chlorine attached to the C60 cage, is applied to modulate the crystallization process and passivate grain boundary defects of the perovskite film. The chemical interactions between C60Cl6 and perovskite components retard the transforming process of precursors to perovskite crystals and obtain a high‐quality tin‐based perovskite film. It is also revealed that the C60Cl6 located at the surfaces and grain boundaries can not only passivate the defects but also offer a role in suturing grain boundaries to suppress the detrimental effects of water and oxygen on perovskite films, especially the oxidation of Sn2+ to Sn4+. As a result, the C60Cl6‐based device yields a remarkably improved device efficiency from 10.03% to 13.30% with enhanced stability. This work provides a new strategy to regulate the film quality and stability of TPSCs using functional fullerene materials. [ABSTRACT FROM AUTHOR]

Multimode luminescence relates to how charge carriers are transported and recombined in response to various physical excitations. It shows promising applications in many fields like advanced anti‐counterfeiting, information storage and encryption. Enabling a stable single compound with multimode luminescence is a unique technology but still remains a challenge. Herein, a versatile and high‐performance energy storage LiTaO3:0.01Tb3+,xGd3+ perovskite is discovered by utilizing the interplay of electron‐trapping defect levels and hole‐trapping Tb3+. It combines an excellent charge carrier storage capacity (≈7 and 12 times higher than state‐of‐the‐art BaFBr(I):Eu2+ and Al2O3:C), >1200 h storage duration, >40 h afterglow, efficient optically stimulated luminescence, persistent mechanoluminescence, and force‐induced charge carrier storage features. Particularly, it well responds to various stimuli channels, i.e., wide‐range X‐rays to 850 nm infrared photons, thermal activation, mechanical force grinding, or compression. To elucidate this multimode luminescence, charge carrier trapping and release processes in LiTaO3:0.01Tb3+,xGd3+ with various physical stimulations will be unraveled by combining the vacuum‐referred binding diagram construction, spectroscopy, thermoluminescence, and mechanoluminescence techniques. The versatile and high‐performance LiTaO3:0.01Tb3+,xGd3+ enables promising proof‐of‐concept multimode luminescence applications in advanced anti‐counterfeiting, flexible X‐ray imaging, continuous compression force sensing, and non‐real‐time recording. [ABSTRACT FROM AUTHOR]