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Abstract DNA helicase activity is essential for the vital DNA metabolic processes of recombination, replication, transcription, translation, and repair. Recently, an unexpected, rapid exponential ATP‐stimulated DNA unwinding rate was observed from anArchaeoglobus fulgidushelicase (AfXPB) as compared to the slower conventional helicases fromSulfolobus tokodaii, StXPB1 and StXPB2. This unusual rapid activity suggests a “molecular wrench” mechanism arising from the torque applied by AfXPB on the duplex structure in transitioning from open to closed conformations. However, much remains to be understood. Here, we investigate the concentration dependence of DNA helicase binding and ATP‐stimulated kinetics of StXPB2 and AfXPB, as well as their binding and activity in Bax1 complexes, via an electrochemical assay with redox‐active DNA monolayers. StXPB2 ATP‐stimulated activity is concentration‐independent from 8 to 200 nM. Unexpectedly, AfXPB activity is concentration‐dependent in this range, with exponential rate constants varying from seconds at concentrations greater than 20 nM to thousands of seconds at lower concentrations. At 20 nM, rapid exponential signal decay ensues, linearly reverses, and resumes with a slower exponential decay. This change in AfXPB activity as a function of its concentration is rationalized as the crossover between the fast molecular wrench and slower conventional helicase modes. AfXPB‐Bax1 inhibits rapid activity, whereas the StXPB2‐Bax1 complex induces rapid kinetics at higher concentrations. This activity is rationalized with the crystal structures of these complexes. These findings illuminate the different physical models governing molecular wrench activity for improved biological insight into a key factor in DNA repair. 

Abstract Perovskite light‐emitting diodes (PeLEDs) are advancing because of their superior external quantum efficiencies (EQEs) and color purity. Still, additional work is needed for blue PeLEDs to achieve the same benchmarks as the other visible colors. This study demonstrates an extremely efficient blue PeLED with a 488 nm peak emission, a maximum luminance of 8600 cd m⁻², and a maximum EQE of 12.2% by incorporating the double‐sided ethane‐1,2‐diammonium bromide (EDBr₂) ligand salt along with the long‐chain ligand methylphenylammonium chloride (MeCl). The EDBr₂successfully improves the interaction between 2D perovskite layers by reducing the weak van der Waals interaction and creating a Dion–Jacobson (DJ) structure. Whereas the pristine sample (without EDBr₂) is inhibited by small stacking number (n) 2D phases with nonradiative recombination regions that diminish the PeLED performance, adding EDBr₂successfully enables better energy transfer from smallnphases to largernphases. As evidenced by photoluminescence (PL), scanning electron microscopy (SEM), and atomic force microscopy (AFM) characterization, EDBr₂improves the morphology by reduction of pinholes and passivation of defects, subsequently improving the efficiencies and operational lifetimes of quasi‐2D blue PeLEDs. 

Abstract Light‐emitting electrochemical cells (LECs) are devices that utilize efficient ion redistribution to produce high‐efficiency electroluminescence in a simple device architecture. Prototypical polymer LECs utilize three components in the active layer: a luminescent conducting polymer, a salt, and an electrolyte. Similarly, many small‐molecule LECs also utilize an electrolyte to disperse salts. In these systems, the electrolyte is incorporated to efficiently conduct ions and to maintain phase compatibility between all components. However, certain LEC approaches and materials systems enable device operation without a dedicated electrolyte. This review describes the general methods and materials used to circumvent the use of a dedicated electrolyte in LECs. The techniques of synthetically coupling electrolytes, incorporating ionic liquids, and introducing inorganic salts are presented in view of research efforts to date. The use of these techniques in emerging classes of light‐emitting electrochemical cells is also discussed. These approaches have yielded some of the most efficient, long‐lasting, and commercially applicable LECs to date.