Deokjae Choi1,Namwoo Kim1,Hyungwoo Kim1,Han-Don Um2,Kwanyong Seo1
Ulsan National Institute of Science and Technology1,Kangwon National University2
Deokjae Choi1,Namwoo Kim1,Hyungwoo Kim1,Han-Don Um2,Kwanyong Seo1
Ulsan National Institute of Science and Technology1,Kangwon National University2
Structural optimization of microwire arrays is important for the successful demonstration of the practical feasibility of radial junction crystalline silicon (c-Si) solar cells. In this study, we investigated an optimized design of tapered microwire (TMW) arrays to maximize the light absorption of c-Si solar cells, while minimizing the surface recombination, for simultaneously improving the open-circuit voltage and short-circuit current density (<i>J<sub>sc</sub></i>). Finite-difference time-domain simulations confirmed that controlling the spacing between the TMWs at the nanometer scale is more effective for increasing the light absorption than increasing the TMW length. The photogenerated current of a c-Si TMW array with a 200 nm spacing was calculated to be 42.90 mA/cm<sup>2</sup>, which is close to the theoretical limit of 43.37 mA/cm<sup>2</sup> in the 300–1100 nm wavelength range. To experimentally demonstrate the TMW arrays with a nanometer-scale spacing of 200 nm, which cannot be realized by conventional photolithography, we utilized a soft lithography method based on polystyrene beads for patterning a c-Si wafer. The solar cells based on optimized TMW arrays exhibited a <i>J<sub>sc</sub></i> of 42.5 mA/cm<sup>2</sup> and power conversion efficiency of 20.5%, which exceed those of the previously reported microwire-based radial junction solar cells.