Heteroepitaxial and homoepitaxial nucleation strategies to grow Sb₂ S₃ nanorod arrays and therefrom a derived gain of 7.18%-efficient Sb₂ (S,Se)₃ quasi-nanoarray heterojunction solar cells

Narrow-bandgap semiconductor nanoarrays are the promising photon-harvesters for photovoltaics because of their unique optoelectronic properties. To prepare the solution-processed nanoarrays of antimony sulfide (Sb2S3) and antimony selenosulfide (Sb2(S,Se)3) that are of a great potential in photovoltaics are still challenging. Here, a tiny-Sb2Se3-seed assisted solution-processing method for growing Sb2S3) nanorod array (NA) on non-epitaxial-for-seed-growth substrates is developed for the first time, complementing the tiny-Sb2S3)-seed-derived Sb2Se3-NA growth on TiO2 nanoparticle film that is actually epitaxial for the Sb2S3) seed growth. The orientation-competing-epitaxial nucleation/growth mechanisms based on the heteroepitaxial and homoepitaxial nucleation effects of randomly formed tiny seeds are proposed for, respectively, understanding the tiny-Sb2Se3-seed-derived Sb2Se3-NA growth and the unavailable tiny-Sb2S3)- seed-derived Sb2Se3-NA or tiny-Sb2Se3-seed-derived Sb2Se3-NA growth on non-epitaxial-for-seed-growth substrates. Moreover, the homoepitaxial nucleation effect of epitaxially formed tiny seeds is specified to the tiny-Sb2Se3-seed-derived Sb2Se3-NA growth on TiO(2 )nanoparticle film. Selenization of the tiny-Sb2Se3- seed-derived Sb2Se3/TiO2 nanoarray heterojunction (Sb2Se3/TiO2-NHJ) renders a novel Sb-2(S,Se)3/TiO2 quasinanoarray heterojunction (Sb-2(S,Se)(3)/TiO2-quasi-NHJ), and a champion power conversion efficiency of 7.18% is achieved in the Sb2(S,Se)3/TiO2-quasi-NHJ solar cells with an optimized S/Se atomic ratio of ca. 1/1 obtained by the selenization at 300 degrees C. This paper not only demonstrates the facile solution processing methods to prepare quality NHJ and quasi-NHJ systems for optoelectronic applications, but also is expected to guide the conceptual design for semiconductor nanorod array growth. (C) 2022 Elsevier Ltd. All rights reserved.