The primary challenge regarding solid polymer electrolytes (SPEs) is the development of materials with enhanced mechanical modulus without sacrificing ionic conductivity. Here, we demonstrate that when stiff/rigid polymer nanoparticles that are thermodynamically miscible with a polymer are utilized in a blend with a liquid electrolyte, the elastic modulus and the ionic conductivity of the resulting SPEs increase compared to the linear polymer blend analogues. In particular, when poly­(methyl methacrylate), PMMA, nanoparticles, composed of high functionality star-shaped PMMA, were added to low molecular weight poly­(ethylene oxide), PEO, doped with bis­(trifluoromethane)­sulfonamide (LiTFSI), the resulting SPEs exhibit 2 orders of magnitude higher conductivity and 1 order of magnitude higher mechanical strength compared to their linear PMMA blend analogues. In addition, the former remain solidlike over an extended temperature range. Key to their performance is the morphology that stems from the ability of the PMMA nanoparticles to disperse within the liquid electrolyte host, allowing for the formation of a highly interconnected network of pure liquid electrolyte that leads to high ionic conductivity (comparable to that of the neat PEO electrolyte). The present strategy offers tremendous potential for the design of all-polymer electrolytes with optimized mechanical properties and ionic conductivity over a wide temperature window for advanced electrochemical devices.

Recent efforts in the field of organic photodetectors (OPD) have been focused on extending broadband detection into the near-infrared (NIR) region. Here, two blends of an ultralow bandgap push-pull polymer TQ-T combined with state-of-the-art non-fullerene acceptors, IEICO-4F and Y6, are compared to obtain OPDs for sensing in the NIR beyond 1100 nm, which is the cut off for benchmark Si photodiodes. It is observed that the TQ-T:IEICO-4F device has a superior IR responsivity (0.03 AW -1 at 1200 nm and -2 V bias) and can detect infrared light up to 1800 nm, while the TQ-T:Y6 blend shows a lower responsivity of 0.01 AW -1 . Device physics analyses are tied with spectroscopic and morphological studies to link the superior performance of TQ-T:IEICO-4F OPD to its faster charge separation as well as more favorable donor-acceptor domains mixing. In the polymer blend with Y6, the formation of large agglomerates that exceed the exciton diffusion length, which leads to high charge recombination, is observed. An application of these devices as biometric sensors for real-time heart rate monitoring via photoplethysmography, utilizing infrared light, is demonstrated.

For the next generation of safe and high energy rechargeable lithium metal batteries, we introduce nanostructured polymer particles of asymmetric miktoarm star copolymers as additives to liquid electrolytes for use as solid polymer electrolytes (SPE). The mechanical properties of the resulting SPEs are dramatically improved compared to the pure liquid electrolyte (the elastic modulus increased by up to 8 orders of magnitude), while the ionic conductivity was maintained close to that of the pure liquid electrolyte. In particular, the addition of 44 wt % miktoarm stars, composed of ion conducting poly­(ethylene oxide), PEO, arms that complement stiff insulating polystyrene arms, PS ((PS) n (PEO) n , where n = 30 the number of arms), in a low molecular weight PEO doped with lithium bis­(trifluoro­methane)­sulfonamide (LiTFSI), resulted in SPEs with a shear modulus of G′ ∼ 0.1 GPa and ion conductivity σ ∼ 10–4 S/cm. The SPEs show a strong decoupling between the mechanical behavior and the ionic conductivity as G′ remains fairly constant for temperatures up to the glass transition temperature of the PS blocks, while the conductivity monotonically increases reaching σ ∼ 10–2 S/cm. Our strategy offers tremendous potential for the design of all-polymer nanostructured materials with optimized mechanical properties and ionic conductivity over a wide temperature window for advanced lithium battery technology.

Herein, we report a detailed study on the optoelectronic properties, photovoltaic performance, structural conformation, morphology variation, charge carrier mobility, and recombination dynamics in bulk heterojunction solar cells comprising a series of donor–acceptor conjugated polymers as electron donors based on benzodithiophene (BDT) and 5,8-bis­(5-bromothiophen-2-yl)-6,7-difluoro-2,3-bis­(3-(octyloxy)­phenyl)­quinoxaline as a function of the BDT’s thienyl substitution (alkyl (WF3), alkylthio (WF3S), and fluoro (WF3F)). The synergistic positive effects of the fluorine substituents on the minimization of the bimolecular recombination losses, the reduction of the series resistances (R S), the increment of the shunt resistances (R Sh), the suppression of the trap-assisted recombination losses, the balanced charge transport, the finer nanoscale morphology, and the deeper highest occupied molecular orbital (E HOMO) are manifested versus the alkyl and alkylthio substituents. According to these findings, the WF3F:[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM)-based organic photovoltaic device is a rare example that features a high power conversion efficiency (PCE) of 17.34% under 500 lx indoor light-emitting diode light source with a high open-circuit voltage (V OC) of 0.69 V, due to the suppression of the voltage losses, and a PCE of 9.44% at 1 sun (100 mW/cm2) conditions, simultaneously.