Broadening the optical absorption of organic photovoltaic (OPV) materials by enhancing the intramolecular push-pull effect is a general and effective method to improve the power conversion efficiencies of OPV cells. However, in terms of the electron acceptors, the most common molecular design strategy of halogenation usually results in down-shifted molecular energy levels, thereby leading to decreased open-circuit voltages in the devices. Herein, we report a chlorinated non-fullerene acceptor, which exhibits an extended optical absorption and meanwhile displays a higher voltage than its fluorinated counterpart in the devices. This unexpected phenomenon can be ascribed to the reduced non-radiative energy loss (0.206 eV). Due to the simultaneously improved short-circuit current density and open-circuit voltage, a high efficiency of 16.5% is achieved. This study demonstrates that finely tuning the OPV materials to reduce the bandgap-voltage offset has great potential for boosting the efficiency.

We demonstrate a facile and environmentally friendly approach to prepare well-dispersed graphene sheets by g-ray induced reduction of a graphene oxide (GO) suspension in N,N-dimethyl formamide (DMF) at room temperature. GO is reduced by the electrons generated from the radiolysis of DMF under g-ray irradiation. The reduced GO by g-ray irradiation (G-RGO) can be re-dispersed in many organic solvents, and the resulting suspensions are stable for two weeks due to the stabilization of N(CH 3 ) 2 + groups on G-RGO. Additionally, G-RGO is efficient in improving the conductivity of polystyrene (PS). Its PS nanocomposites exhibit a sharp transition from electrically insulating to conducting with a low percolation threshold of 0.24 vol% and a high electrical conductivity of 45 S m À1 is obtained with only 2.3 vol% of G-RGO. The superior electrical conductivity is attributed to the uniform dispersion of the G-RGO sheets in the PS matrix.

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High-performance hydrogel electrolytes play a crucial role in flexible supercapacitors (SCs). However, the unsatisfactory mechanical properties of widely used polyvinyl alcohol-based electrolytes greatly limit their use in the flexible SCs. Here, a novel LiSO-containing agarose/polyacrylamide double-network (Li-AG/PAM DN) hydrogel electrolyte was synthesized by a heating-cooling and subsequent radiation-induced polymerization and cross-linking process. The Li-AG/PAM DN hydrogel electrolyte possesses extremely excellent mechanical properties with a compression strength of 150 MPa, a fracture compression strain of above 99.9%, a tensile strength of 1103 kPa, and an elongation at break of 2780%, greatly superior to those have been reported. It also achieves a high ionic conductivity of 41 mS cm originating from its interconnected three-dimensional porous network structure that provides a three-dimensional channel for ionic migration. Compared to the SC applying LiSO aqueous solution electrolyte, the corresponding flexible Li-AG/PAM DN hydrogel electrolyte-SC presents lower charge-transfer resistance, better ionic diffusion, being closer to ideal capacitive behaviors, superior rate capability, and better cycling stability, owing to the improved ionic transport in the Li-AG/PAM DN hydrogel electrolyte and electrode interfaces. Moreover, after testing with overcharge, short circuit, and high temperature, the capacitance of the Li-AG/PAM DN hydrogel electrolyte-SC can still be well maintained. Furthermore, the electrochemical properties of the Li-AG/PAM DN hydrogel electrolyte-SC remain almost intact under different compression strains/bending angles and even after 1000 compression/bending cycles. It is expected that the Li-AG/PAM DN hydrogel electrolyte may have broad applications in modern flexible and wearable electronics.

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Currently, adhesive and self-healable hydrogels have highlighted their potential in tissue adhesives, sealants, and implantable electronic devices. For electronic device adhesives, a combination of adhesive, conductive, and selfhealing properties is required. Here, we demonstrated a onepot synthesis method of a novel self-healing hydrogel (named GO x SPNB) with various ratios of graphene oxide to soluble starch and poly(sodium 4-vinyl-benzenesulfonate-co-N-(2-(methacryloyloxy)ethyl)-N,N-dimethylbutan-1-aminium bromide) by a γ-radiation technique. The resultant hydrogel based on a totally physical cross-linking network exhibits fast automatic self-healing ability, nontoxicity, ionic conductivity about 10.5 mS dm −1 , and super highly reusable metal adhesion with 60.5 MPa adhesive strength to the copper plates at room temperature, nearly one magnitude larger than other reversible adhesives that have been reported. Meanwhile, it also shows extreme adhesive strength to some organic substrates, such as porcine skin (130.70 kPa) which is the highest strength to date. This self-healable adhesive hydrogel, especially for metal substrates, has great potential in hydrogel glues for the design and fabrication of smart electronic device adhesives.

The development of fl exible energy devices is dramatically increasing the requirement of gel polymer electrolyte (GPE) with mechanical robustness and excellent transport effi ciency of ion or solute. Some GPEs such as poly(vinylidene fl uoride) (PVDF) with glass fi bers, [ 12 ] nonwoven fabrics, [ 13 ] etc. have been reported for fl exible batteries. There is a remarkable ions migration effi ciency in these GPEs, which provides breakthrough electrochemical performances. Poly(vinyl alcohol) (PVA) hydrogel is a widely used GPE substrate for supercapacitors. [ 5,14 ] However, current ionic conducting gels, which just consist of PVA hydrogels and inorganic salts, acid or alkali dissolved in water, are brittle and exhibit poor mechanical strength due to the damage of inorganic ions to the hydrogen bond between PVA polymer chains and water molecules. Furthermore, metal electrodes can be corroded by acid in the GPE during the charge-discharge process. Therefore, GPE with neutral salts is a promising new research fi eld for semi-solid-state supercapacitors. However, excess inorganic ions would infl uence the mechanical strength of the gels because of the coagulation with PVA chains in water. Consequently, the ionic conductivities of GPE are generally low (0.1-10 mS cm −1 ) due to the limitation of salts content (generally lower than 20 wt%) in gels. Up to date, the problem that inorganic salts cannot be added into gel polymer substrate in large quantities has not been settled.Common neutral GPE contains much water, and the potential window of the aqueous GPE is limited to the ideal maximum value of 1.23 V, usually used in the range of 0-0.80 V which also places restrictions on the application of such supercapacitors. And aqueous GPE cannot maintain a stable appearance with the gradual loss of water which also infl uences the electrochemical behavior of supercapacitors. [ 15 ] Ionic liquids (ILs) recently attain more attention in the applications of energy storage, such as semi-solid-state supercapacitors, because of their wide operation potential, high thermal and electrochemical stability as conducting medium relative to inorganic salts. However, their low conductivities restrict the electrochemical performance in semi-solid-state supercapacitors. [ 1,16,17 ] The ionic conductivity can be improved further with a wide operation electrochemical window after the addition of neutral inorganic salts in the GPE, which opens up new access to high-performance EDLCs, but related researches are lacked.

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