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Abstract All-solid-state sodium batteries (ASSSBs) are promising candidates for grid-scale energy storage. However, there are no commercialized ASSSBs yet, in part due to the lack of a low-cost, simple-to-fabricate solid electrolyte (SE) with electrochemical stability towards Na metal. In this work, we report a family of oxysulfide glass SEs (Na 3 PS 4− x O x , where 0 <  x  ≤ 0.60) that not only exhibit the highest critical current density among all Na-ion conducting sulfide-based SEs, but also enable high-performance ambient-temperature sodium-sulfur batteries. By forming bridging oxygen units, the Na 3 PS 4− x O x SEs undergo pressure-induced sintering at room temperature, resulting in a fully homogeneous glass structure with robust mechanical properties. Furthermore, the self-passivating solid electrolyte interphase at the Na|SE interface is critical for interface stabilization and reversible Na plating and stripping. The new structural and compositional design strategies presented here provide a new paradigm in the development of safe, low-cost, energy-dense, and long-lifetime ASSSBs. 

Organic photovoltaic (OPV) devices offer a number of unique advantages over conventional single crystal silicon solar cells, such as simple and low‐cost fabrication, significantly reduced weight, high flexibility, and semitransparency. However, OPV devices exhibit poor durability to mechanical deformations. Here, the use of an elastic semi‐interpenetrating network is studied to improve the mechanical durability of the active layer of OPV devices based on the high‐performance poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl‐3‐fluoro)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione)]:2,2′‐[[6,6,12,12‐tetrakis(4‐hexylphenyl)‐6,12‐dihydrodithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,8‐diyl]bis[methylidyne(3‐oxo‐1H‐indene‐2,1(3H)‐diylidene)]]bis[propanedinitrile] donor:acceptor blend (PBDBT‐2F:ITIC). The elastic interpenetrating network is synthesized in situ through the UV photoinitiated crosslinking of thiol–ene additives in the active layer. The effects of strain as a function of bending on the network‐stabilized active layer structure are systematically investigated. The elastic interpenetrating network suppresses crack formation and improves durability to high‐curvature and repeated bending deformations. Performance measurements show that network‐stabilized devices outperform pristine devices above a critical bending strain and number of bending deformations. The photovoltaic performance in general decreases with the increase in the network content, and the best performing devices are obtained using network forming reagents that are most compatible with the donor:acceptor system. This work describes an effective route to flexible devices using semi‐interpenetrating polymer networks and provides insight into the design of the networks to maximize photovoltaic performance.

 

Organic–inorganic hybrid perovskites have emerged as promising optoelectronic materials for applications in photovoltaic and optoelectronic devices. Particularly, 2D layer‐structured hybrid perovskites are of great interest due to their remarkable optical and electrical properties, which can be easily tuned by selecting suitable organic and inorganic moieties during the material synthesis. Here, the solution‐phase growth of a large square‐shaped single‐crystalline 2D hybrid perovskite, phenethylammonium lead bromide (C₆H₅C₂H₄NH₃)₂PbBr₄(PEPB), with thickness as few as 3 unit cell layers is demonstrated. Compared to bulk crystals, the 2D PEPB nanocrystals show a major blueshifted photoluminescence (PL) peak at 409 nm indicating an increase in bandgap of 40 meV. Besides the major peak, two new PL peaks located at 480 and 525 nm are observed from the hybrid perovskite nanocrystals. PEPB nanocrystals with different thicknesses show different colors, which can be used to estimate the thickness of the nanocrystals. Time‐resolved reflectance spectroscopy is used to investigate the exciton dynamics, which exhibits a biexponential decay with an amplitude‐weighted lifetime of 16.7 ps. The high‐quality 2D (C₆H₅C₂H₄NH₃)₂PbBr₄nanocrystals are expected to have high PL quantum efficiency and potential applications for light‐emitting devices.