First-principles study on the doping effects of nitrogen on the electronic structure and optical properties of Cu₂O

Abstract

Recent experimental literature (Sol. Energ. Mat. Sol. Cells, 2012, 105, 192) has reported that nitrogen doped Cu 2 O is a possible material for novel intermediate band solar cells. The doping effects of nitrogen on the crystal structure, electronic structure, and optical properties of Cu 2 O have been studied by an ultrasoft pseudopotential plane wave method based on first-principles calculations. The results show that nitrogen doping slightly widens the band gap of Cu 2 O, and form an intermediate band in the gap located at about 0.9 eV from the VBM (or CBM). This intermediate band is predominantly formed by hybridization between the N-2p states and the Cu-3d states. N-doped Cu 2 O is very likely to absorb at a maximum across the solar light spectrum, from the near infrared region to the ultraviolet region. Based on these results, N-doped Cu 2 O is considered to be a perfect intermediate band material for a novel kind of solar cells.

Communication: Comparing ab initio methods of obtaining effective U parameters for closed-shell materials

“…However, all U out values are still larger than 14 eV, while all empirically fitted U eff values range from 6 to 8 eV. 10,[15][16][17][18][19] Moreover, the increasing U in parameter should open the band gap and diminish the nonlinear behavior of the density functional, thus leading to smaller U out . This expected decreasing trend is found, e.g., in ferromagnetic (open-shell) bcc Fe calculations 5 but does not occur in the present Cu 2 O case.…”

A Review on Cu<SUB>2</SUB>O and Cu<SUP>I</SUP>-Based <I>p</I>-Type Semiconducting Transparent Oxide Materials: Promising Candidates for New Generation Oxide Based Electronics

“…189 Based on the widening of the band gap of N-doped Cu 2 O, it is very likely that it would absorb at a maximum rate across the solar light spectrum, from the near infrared region to the ultraviolet region, and hence can be considered as a perfect intermediate band (IB) material, which can improvise the solar cell performance. 189 Recently, Mittiga et al 190 first reported that nitrogen doped Cu 2 O could act as a possible material for 3rd generation IB solar cells. …”

Enhanced visible light photocatalytic activity of Cu2O via cationic–anionic passivated codoping

“…Cu 2 O, with an intrinsic direct band gap of 2.17 eV 11 , making it one of the most promising photocatalysts for environmental clean up, photogeneration of hydrogen from water, and solar energy utilization, has been tested as a visible-light driven photocatalyst directly for splitting water and degradation of organic pollutants 12,13 . Further advantages are nontoxicity, low-cost production processing and the fact that its component elements are very abundant 14 . Moreover, the band alignments of Cu 2 O satisfy the requirement as mentioned above with a CBM (-1.4 eV) far above the hydrogen production level (-0.65 eV) and VBM (+0.77 eV) slightly below the water oxidation level (+0.57 eV) at pH=7 (see Figure 1 Unfortunately, the practical application of Cu 2 O in solar hydrogen production is still severely hindered by its low photocatalytic efficiency due to two major reasons: Firstly, the even-parity symmetry of the CBM and VBM states in Cu 2 O prohibits the band-edge radiative transition, which has hindered its potential use in optical applications 11,16,17 .…”