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Abstract Organic emitters that exhibit room‐temperature phosphorescence (RTP) in neat films have application potential for optoelectronic devices, bio‐imaging, and sensing. Due to molecular vibrations or rotations, the majority of triplet excitons recombine rapidly via non‐radiative processes in purely organic emitters, making it challenging to observe RTP in amorphous films. Here, a chemical strategy to enhance RTP in amorphous neat films is reported, by utilizing through‐space charge‐transfer (TSCT) effect induced by intramolecular steric hindrance. The donor and acceptor groups interact via spatial orbital overlaps, while molecular motions are suppressed simultaneously. As a result, triplets generated under photo‐excitation are stabilized in amorphous films, contributing to phosphorescence even at room temperature. The solvatochromic effect on the steady‐state and transient photoluminescence reveals the charge‐transfer feature of involved excited states, while the TSCT effect is further experimentally resolved by femtosecond transient absorption spectroscopy. The designed luminescent materials with pronounced TSCT effect show RTP in amorphous films, with lifetimes up to ≈40 ms, comparable to that in a rigid polymer host. Photoluminescence afterglow longer than 3 s is observed in neat films at room temperature. Therefore, it is demonstrated that utilizing intramolecular steric hindrance to stabilize long‐lived triplets leads to phosphorescence in amorphous films at room temperature. 

Abstract Perovskites have emerged as a forerunner of electronics research due to their vast potential for optoelectronic applications. The numerous combinations of constituent ions and the potential for doping of perovskites lead to a high demand to track the underlying electronic properties. Solution‐based electrochemistry is particularly promising for detailed and facile assessment of perovskites. Here, electrochemical impedance spectroscopy (EIS) of methylammonium lead iodide (MAPbI₃) thin films is performed and model them with an equivalent circuit that accounts for solvent, ionic, and thin film effects. A dielectric constant consistent with prior AC studies and a diffusion constant harmonious with cation motion in MAPbI₃are extracted. An electrical double layer thickness in the perovskite film of 54 nm is obtained, consistent with lithium doping in perovskite films. Comparing the EIS and equivalent circuit model of perovskite films to control ITO‐only data enabled the assignment of the ions at each interface. This comparison implied a double layer of primarily lithium ions inside the perovskite film at the solution interface with significant recombination of ions on the solution side of the interface. This demonstrates EIS as a powerful tool for studying the fundamental charge accumulation and transport processes in perovskite thin films. 

Abstract We report a facile synthesis of diindeno‐fused dibenzo[a,h]anthracene derivatives (DIDBA‐2Cl,DIDBA‐2Ph, andDIDBA‐2H)with different degrees of non‐planarity using three substituents (chloro, phenyl, and hydrogen) of various sizes. The planarization of their cores, as evidenced by the decreased end‐to‐end torsional angles, was confirmed by X‐ray crystallography. Their enhanced energy gaps with twisting were investigated by a combination of spectroscopic and electrochemical methods with density functional theory, which showed a transition from singlet open‐shell to closed‐shell configuration. Moreover, their doubly reduced states,DIDBA‐2Ph²⁻andDIDBA‐2H²⁻, were achieved by chemical reduction. The structures of dianions were identified by X‐ray crystallographic analysis, which elucidated that the electron charging further distorted the backbones. The electronic structure of the dianions was demonstrated by experimental and theoretical approaches, suggesting decreased energy gaps with larger non‐planarity, different from the neutral species. 

Abstract Understanding the structure‐function relationships of the green fluorescent protein (GFP) chromophore is important in rationally developing new molecular tools for biological imaging and beyond. Herein, we systematically modified the GFP chromophore structure with electron‐withdrawing and ‐donating groups (EWGs and EDGs) to investigate the substituent effects on the excited‐state proton transfer (ESPT) and twisting dynamics of the cationic chromophore in solution. With key insights gained from femtosecond transient absorption and stimulated Raman spectroscopy, we reveal that the EWG substitution by –F increases photoacidity in an additive manner and leads to an ultrafast barrierless ESPT by difluorination, while the EDG substitution by –OCH₃also results in ultrafast ESPT despite the weak photoacidity as estimated by the Förster equation. We ascribe the unusually fast kinetics in methoxylated derivatives to the occurrence of a pre‐existing chromophore‐solvent complex that sets up the acceptor site for ESPT. Furthermore, the kinetic competition between ESPT and twisting pathways is crucial for the observation of ESPT in action, particularly for molecules undergoing efficient nonradiative decay in the excited state through torsional motions. Such flexible and highly engineerable molecules can enable more versatile photoswitches and sensors. 

Abstract Phosphane, PH₃—a highly pyrophoric and toxic gas—is frequently contaminated with H₂and P₂H₄, which makes its handling even more dangerous. The inexpensive metal–organic framework (MOF) magnesium formate, α‐[Mg(O₂CH)₂], can adsorb up to 10 wt % of PH₃. The PH₃‐loaded MOF, PH₃@α‐[Mg(O₂CH)₂], is a non‐pyrophoric, recoverable material that even allows brief handling in air, thereby minimizing the hazards associated with the handling and transport of phosphane. α‐[Mg(O₂CH)₂] further plays a critical role in purifying PH₃from H₂and P₂H₄: at 25 °C, H₂passes through the MOF channels without adsorption, whereas PH₃adsorbs readily and only slowly desorbs under a flow of inert gas (complete desorption time≈6 h). Diphosphane, P₂H₄, is strongly adsorbed and trapped within the MOF for at least 4 months. P₂H₄@α‐[Mg(O₂CH)₂] itself is not pyrophoric and is air‐ and light‐stable at room temperature.