A method for fabricating high-efficiency Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells is presented, and it is based on a nonexplosive, low-cost, and simple solution process followed by a two-step heat treatment. 2-Methoxyethanol was used as a solvent, and Cu, Zn, Sn, chloride salts, and thiourea were used as solutes. A CZTSSe absorber was prepared by sulfurising and then selenising an as-coated Cu 2 ZnSnS 4 (CZTS) film. Sulfurisation in a sulfur vapour filled furnace for a long time (2 h) enhanced the crystallisation of the as-coated CZTS film and improved the stability of the CZTS precursor, and selenisation promoted further grain growth to yield a void-free CZTSSe film. Segregation of Cu and S at the grain boundaries, the absence of a fine-grain bottom layer, and the large grain size of the CZTSSe absorber were the main factors that enhanced the grain-to-grain transport of carriers and consequently the short-circuit current (J sc ) and efficiency. The efficiency of the CZTS solar cell was 5.0%, which increased to 10.1% after selenisation. For the 10.1% CZTSSe solar cell, the external quantum efficiency was approximately 80%, the open-circuit voltage was 450 mV, the short-circuit current was 36.5 mA/cm 2 , and the fill factor was 61.9%.

To obtain the cross sections of the 9Be(d, t)8Be reaction, a thick beryllium target was bombarded with a deuteron beam from 78 to 100 keV, with an energy step of 2 keV. The charged particles emitted from the d-9Be interaction were accumulated, and the cross sections were deduced from the thick-target yields of emitted tritium. The present work, in conjunction with the data reported in the high-energy region, extended the directly measured values of cross section to 65 keV in the center-of-mass system, thereby filling in the nuclear data gap in the low-energy region.

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