标题：Improved opticalabsorption of silicon single-nanowire solar cells by off-axial core/shelldesign
作者：Cheng Zhang, Zhenhai Yang, Aixue Shang, Shaolong Wu,Yaohui Zhan, and Xiaofeng Li*
Single-nanowire solar cells (SNSCs) areattracting increasing interest due to their unique antenna-effect-mediated light-trappingand the efficient charge separation through thin semiconductor junctions.However, for such newly emerging photovoltaic devices, the optical andphotoconversion performance is still far from the expectation. More effectivestrategies which are capable of providing broadband/high absorption and highelectrical outcome are strongly desired. In this study, we introduce theconcept of symmetry-breaking into the core/shell silicon SNSCs, which enables asubstantially enhanced optical absorption under an improved coupling betweenthe photoactive material and the focus of the dielectric shell. By properlydeviating the silicon core away from the dielectric shell center (i.e., theoff-axial core/shell design), the light-trapping capability of the device issignificantly improved in almost the whole spectral band without degrading thecarrier collection performance. Our optoelectronic simulation exhibits that thephotocurrent density as well as the light-conversion efficiency offree-standing SNSCs can be doubled (enhanced by ~40%) compared to that of thesystem under bare (co-axial core/shell) nanowire design; moreover, the deviceperformance under such asymmetric design can be further improved withintroducing the metal-coated substrate.