Hanyu Yao

A 4.92% efficiency Cu2ZnSnS4 solar cell from nanoparticle ink and molecular solution

Quaternary Cu2ZnSnS4 (CZTS) thin films were prepared by a low-cost, simple and environmentally-friendly ink method. By depositing molecular solution on the nanoparticle thin film, the quality of as-prepared CZTS thin films was greatly improved (e.g. reduction of fine grain layer formation and improved crystallinity). The effect of the number of spin-coated layers from molecular solution on solar cell performance was investigated. The results indicated that the CZTS thin film had the best performance when 5 layers were spin-coated from molecular solution on the nanoparticle thin film. The crystallinity of the as-prepared CZTS thin film and the interface at Mo/CZTS was found to be obviously enhanced by addition of a molecular solution layer. Finally, a CZTS thin film solar cell with an efficiency of 4.92% has been fabricated.

Efficient light trapping of quasi-inverted nanopyramids in ultrathin c-Si through a cost-effective wet chemical method

In this paper, we report quasi-inverted nanopyramids (QIP) for light-trapping in ultrathin c-Si by a cost-effective wet chemical method. The QIP is fabricated by a well-known two-step Ag assisted chemical etching method followed by a post nanostructure rebuilding (NSR) process, lowering the surface area to ∼3.0 times for suppressing surface recombination losses. The comparable average absorptance value of 43 μm c-Si with double-sided QIP to that of 182 μm c-Si with double-sided conventional pyramid in the spectral range of 300–1100 nm demonstrates an over 4.2-fold reduction in material usage. Finally, a simulation model is proposed to explain the superiority of our QIP compared with the periodic inverted pyramid (IP) structure of the same size, presenting a promising method to the mass production of high-efficiency ultrathin c-Si HIT solar cells.