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• Ga doping is applied to the tailor residual stress of flexible CZTSSe thin film. • Alleviated residual stress contributes a superior microstructure of CZTSSe. • Evaporated 20 nm Ga layer exhibits the best PCE with satisfying bending durability. Ga-doped CZTSSe is achieved by evaporating Ga layer in precursor combined with subsequent selenization to balance the efficiency and bending durability of flexible CZTSSe solar cells in this paper. Ga doping can simultaneously alleviate the residual stress and reinforce the microstructure of CZTSSe, retaining the original lattice structure of CZTSSe and suppressing Sn-related deep level defects. The gratifying residual stress reduction from -5.31 GPa to -3.82 GPa with decreased porosity from 6.24% to 3.24% of CZTSSe thin film spontaneously promotes the device performance after evaporating the 20 nm Ga layer. A desirable efficiency enhancement from 2.61% to 5.04% with preferable bending durability of flexible device is achieved, which strategy provides substantial assistance for the potential application of flexible solar cells. [ABSTRACT FROM AUTHOR]

• TiN-Al 2 O 3 -Cr gradient layer is introduced to tailor residual stress of CZTSSe. • 60 nm sputtered gradient layer contributes the best heterojunction characteristic. • Gradient layer introduced device exhibits more satisfying bending stability. In an effort to promote the mechanical endurance of flexible Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells, a convenient and effective strategy for introducing a TiN-Al 2 O 3 -Cr gradient layer is proposed, which can effectively tailor the residual stress and improve the heterojunction characteristic of solar cell. Benefitted from the optimum TiN-Al 2 O 3 -Cr gradient layer with 60 nm, CZTSSe presents a released residual stress of −3.33 GPa and an optimized heterojunction characteristic with the CBO of −0.28 eV. Furthermore, the PCE of flexible device is remarkably improved from 3.31 % to 5.01 %, which can maintain 85 % of the original efficiency after harsh bending. The proposed gradient layer strategy may pave a thriving way for congener flexible and portable cells. [ABSTRACT FROM AUTHOR]

Photoelectrochemical oxidation of methyl phenyl sulfide with water as the only oxygen source is achieved on Mo-BiVO 4 photoanode. Mo-BiVO 4 photoelectrode performs oxygen transfer reaction in PEC oxidation of MPS. [Display omitted] • Mo-BiVO 4 photoelectrode was applied to oxidation of methyl phenyl sulfide. • PEC oxygen atom transfer (OAT) reaction was achieved on Mo-BiVO 4 photoelectrode. • Isotopic labelling experiment with H 2 18O revealed oxygen atoms in MPSO were mainly from water. Photoelectrochemical (PEC) selective oxidation is an environment-friendly strategy to obtain value-added chemicals. Herein, we report the PEC oxidation of methyl phenyl sulfide (MPS) into methyl phenyl sulfoxide (MPSO) with 85.7 % selectivity and 36.2 % conversion on molybdenum doped bismuth vanadate (Mo-BiVO 4) photoelectrode under simulated sunlight illumination (AM 1.5 G, 100 mW cm−2). Isotopic labelling experiment with H 2 18O was conducted to clearly reveal that the oxygen atoms in the MPSO were mainly from water. Based on these results, the application of Mo-BiVO 4 has been extended to PEC selective oxidation. [ABSTRACT FROM AUTHOR]

• α-Fe 2 O 3 photoanode was modified by antimony. • Ethylene glycol was an excellent solvent for antimony treatment. • The α-Fe2O3 photoanodes combined with antimony post-treatment showed the best photoelectrochemical performance. The photoelectrochemical (PEC) performance of α-Fe 2 O 3 photoanode suffers from the high carrier recombination rate and the short hole diffusion distance. Enhancing its carrier transport is an important way to improve its performance. In this paper, α-Fe 2 O 3 films were synthesized by hydrothermal method and further optimized by ethylene glycol assisted antimony treatment. Antimony treatment can be divided into pre-annealing and post-annealing treatment. The photocurrent of hematite photoanode post-annealing treated by Sb dissolved in ethylene glycol photoanode can reach to 1.18 mA cm−2, which is 1.6 times higher than that of bare α-Fe 2 O 3 photoanode. The improvement of PEC performance is mainly attributed to the effective inhibition of carrier recombination by antimony treatment. In addition, the slope of the Mott-Schottky curves of Fe 2 O 3 can be obviously changed by antimony treatment, demonstrating the significant increase of carrier concentration. [ABSTRACT FROM AUTHOR]