@techreport{oai:kanazawa-u.repo.nii.ac.jp:00011973,
 month = {May},
 note = {Ferroelectric materials are new candidates for photovoltaic materials. Ferroelectrics can produce photocurrents without using p-n junction which is necessary for conventional photo-voltaic devices. BiFeO3 is one of the most promising multiferroic materials having band gap of 2.5 eV. This band gap is too wide to be used as photovoltaic devices, therefore lower band gap is necessary. In order to reduce BiFeO3 band gap, we carry out a first-principles calculation. We study Cu substitution impurities. We introduce a single Cu atom in the 2x2x2 supercell and we find that the band gap is reduced by 0.039 eV. We expect the existence of optical transition energy between valence and impurity band with energy value 1.232 eV lower than the band gap of BiFeO3., Selected Papers from the International Symposium on Computational Science - International Symposium on Computational Science Kanazawa University, Japan, 金沢大学ナノマテリアル研究所 / 金沢大学理工研究域数物科学系},
 title = {Multiferroic BiFeO3 for Photovoltaic Applications : A First-principles Study},
 year = {2015}
}