Yangqin Gao,Guoqing Yang,Yanjie Dai,Xuli Li,Jianfeng Gao,Ning Li,Ping Qiu,Lei Ge
Co-substituted LaFeO3 was electrodeposited on the surface of BiVO4 as a co-catalyst to enhance the water splitting performance. Compared to bare BiVO4, the BiVO4/Co-LaFeO3 composite photoanode shows a water oxidation photocurrent of 3.4 mA/cm2 at 1.23 V versus reverse hydrogen electrode, accompanied by a notable cathodic shift in the onset potential for 300 mV. Combined optical and electrochemical characterizations show that the solid/electrolyte charge transfer efficiency of BiVO4 are dramatically improved by the incorporation of Co-substituted LaFeO3. From the surface kinetic study of charge carriers by intensity-modulated photocurrent spectroscopy, a suppressed surface recombination rate constant is observed and the enhanced photoelectrochemical water splitting performance observed in the BiVO4/Co-LaFeO3 photoanode is attributed to the surface passivation effect of Co-substituted LaFeO3.
As compared to the predecessor Cu(In,Ga)Se 2 device, the current efficiency of kesterite Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells is still much lower mainly due to the known carriers recombination issue within interface and absorber bulk. In contrast to the majority of researches concerning recombination issues that focus on either single absorber bulk or interface passivation strategy, this study is pioneering in constructing synergistic passivation effects (SPE) to address the bulk and interface recombination issue simultaneously. By introducing a novel niobium pentoxide passivation layer into the back electrode interface (BEI), it is identified that SPE can be constructed due to Nb (& O) diffusion from Nb 2 O 5 layer to absorber bulk and BEI during high-temperature selenization. The chemical passivation effect is fulfilled via the intrinsic high resistance characteristic of Nb 2 O 5 layer, and also through the NbO x passivation aiming to absorber bulk benefited from Nb (& O) diffusion. Meanwhile, the occupations of Nb (& O) on the Mo (& Se) sites induce a conduction type inversion in MoSe 2 interfacial layer and create a preferable interface p + -Mo(Se,O) 2 :Nb/CZTSSe, achieving an interfacial field passivation effect. Ultimately, the promoted absorber quality and improved charge carrier transportation from SPE contribute to the boost of device performance beyond 10% efficiency.
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