@article {990,
	title = {Assessing the role of hydrogen in Fermi-level pinning in chalcopyrite and kesterite solar absorbers from first-principles calculations},
	journal = {Journal of Applied Physics},
	volume = {123},
	year = {2018},
	note = {<p>{\textquoteright}doi: 10.1021/acsenergylett.0c01132\n - I.Am.Hydrogen{\textquoteright} {\textquoteright}\n - jyoungstrom{\textquoteright} {\textquoteright}Jason thinks this is great.\n\&nbsp;\n - jyoungstrom{\textquoteright} {\textquoteright}\n - estechel{\textquoteright}</p>},
	pages = {161408},
	abstract = {<p>Publshed on March 7th, 2018. Understanding the impact of impurities in solar absorbers is critical to engineering high-performance in devices, particularly over extended periods of time. Here, we use hybrid functional calculations to explore the role of hydrogen interstitial (Hi) defects in the electronic properties of a number of attractive solar absorbers within the chalcopyrite and kesterite families to identify how this common impurity may influence device performance. Our results identify that Hi can inhibit the highly p-type conditions desirable for several higher-band gap absorbers and that H incorporation could detrimentally affect the open-circuit voltage (Voc) and limit device efficiencies. Additionally, we find that Hi can drive the Fermi level away from the valence band edge enough to lead to n-type conductivity in a number of chalcopyrite and kesterite absorbers, particularly those containing Ag rather than Cu. We find that these effects can lead to interfacial Fermi-level pinning that can qualitatively explain the observed performance in high-Ga content CIGSe solar cells that exhibit saturation in the Voc with increasing band gap. Our results suggest that compositional grading rather than bulk alloying, such as by creating In-rich surfaces, may be a better strategy to favorably engineering improved thin-film photovoltaics with larger-band gap absorbers.</p>},
	issn = {0021-8979},
	doi = {10.1063/1.5006272},
	url = {https://aip.scitation.org/doi/10.1063/1.5006272},
	author = {J. B. Varley and V. Lordi and T. Ogitsu and A. Deangelis and K. Horsley and N. Gaillard}
}
