{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"submitter":["Malik Z"],"funding":["European Research Council","Engineering and Physical Sciences Research Council"],"pagination":["17574-17586"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC11440232"],"repository":["biostudies-literature"],"omics_type":["Unknown"],"volume":["12(43)"],"pubmed_abstract":["The optoelectronic properties of two layered copper oxyselenide compounds, with nominal composition Sr<sub>2</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub> and Ba<sub>2</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub>, have been investigated to determine their suitability as p-type conductors. The structure, band gaps and electrical conductivity of pristine and alkali-metal-doped samples have been determined. We find that the strontium-containing compound, Sr<sub>2</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub>, adopts the expected tetragonal <i>Sr</i> <sub><i>2</i></sub> <i>Mn</i> <sub><i>3</i></sub> <i>SbO</i> <sub><i>2</i></sub> structure with <i>I</i>4/<i>mmm</i> symmetry, and has a band gap of 2.16 eV, and a room temperature conductivity of 4.8 × 10<sup>-1</sup> S cm<sup>-1</sup>. The conductivity of the compound could be increased to 4.2 S cm<sup>-1</sup> when sodium doped to a nominal composition of Na<sub>0.1</sub>Sr<sub>1.9</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub>. In contrast, the barium containing material was found to have a small zinc oxide deficiency, with a sample dependent compositional range of Ba<sub>2</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub> where 0.01 < <i>x</i> < 0.06, as determined by single crystal X-ray diffraction and powder neutron diffraction. The barium-containing structure could also be modelled using the tetragonal <i>I</i>4/<i>mmm</i> structure, but significant elongation of the oxygen displacement ellipsoid along the Zn-O bonds in the average structure was observed. This indicated that the oxide ion position was better modelled as a disordered split site with a displacement to change the local zinc coordination from square planar to linear. Electron diffraction data confirmed that the oxide site in Ba<sub>2</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub> does not adopt a long range ordered arrangement, but also that the idealised <i>I</i>4/<i>mmm</i> structure with an unsplit oxide site was not consistent with the extra reflections observed in the electron diffractograms. The band gap and conductivity of Ba<sub>2</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub> were determined to be 2.22 eV and 2.0 × 10<sup>-3</sup> S cm<sup>-1</sup> respectively. The conductivity could be increased to 1.5 × 10<sup>-1</sup> S cm<sup>-1</sup> with potassium doping in K<sub>0.1</sub>Ba<sub>1.9</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub>. Hall measurements confirmed that both materials were p-type conductors with holes as the dominant charge carriers."],"journal":["Journal of materials chemistry. C"],"pubmed_title":["Observation and enhancement through alkali metal doping of p-type conductivity in the layered oxyselenides Sr<sub>2</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub> and Ba<sub>2</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub>."],"pmcid":["PMC11440232"],"funding_grant_id":["EP/W032244/1","EP/P020194/1","EP/T011793/1","EP/R029431","758345","EP/T022213/1","EP/W032260/1","EP/T027991/1","EP/L000202","EP/T022108/1"],"pubmed_authors":["Gal ZA","Smyth RD","Huang R","Newbrook DW","Kemp L","Blandy JN","Herkelrath SJC","Davies DW","Hyett G","Broadley S","Clarke SJ","Malik Z","Scanlon DO","Rutt G","Hadermann J"],"additional_accession":[]},"is_claimable":false,"name":"Observation and enhancement through alkali metal doping of p-type conductivity in the layered oxyselenides Sr<sub>2</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub> and Ba<sub>2</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub>.","description":"The optoelectronic properties of two layered copper oxyselenide compounds, with nominal composition Sr<sub>2</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub> and Ba<sub>2</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub>, have been investigated to determine their suitability as p-type conductors. The structure, band gaps and electrical conductivity of pristine and alkali-metal-doped samples have been determined. We find that the strontium-containing compound, Sr<sub>2</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub>, adopts the expected tetragonal <i>Sr</i> <sub><i>2</i></sub> <i>Mn</i> <sub><i>3</i></sub> <i>SbO</i> <sub><i>2</i></sub> structure with <i>I</i>4/<i>mmm</i> symmetry, and has a band gap of 2.16 eV, and a room temperature conductivity of 4.8 × 10<sup>-1</sup> S cm<sup>-1</sup>. The conductivity of the compound could be increased to 4.2 S cm<sup>-1</sup> when sodium doped to a nominal composition of Na<sub>0.1</sub>Sr<sub>1.9</sub>ZnO<sub>2</sub>Cu<sub>2</sub>Se<sub>2</sub>. In contrast, the barium containing material was found to have a small zinc oxide deficiency, with a sample dependent compositional range of Ba<sub>2</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub> where 0.01 < <i>x</i> < 0.06, as determined by single crystal X-ray diffraction and powder neutron diffraction. The barium-containing structure could also be modelled using the tetragonal <i>I</i>4/<i>mmm</i> structure, but significant elongation of the oxygen displacement ellipsoid along the Zn-O bonds in the average structure was observed. This indicated that the oxide ion position was better modelled as a disordered split site with a displacement to change the local zinc coordination from square planar to linear. Electron diffraction data confirmed that the oxide site in Ba<sub>2</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub> does not adopt a long range ordered arrangement, but also that the idealised <i>I</i>4/<i>mmm</i> structure with an unsplit oxide site was not consistent with the extra reflections observed in the electron diffractograms. The band gap and conductivity of Ba<sub>2</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub> were determined to be 2.22 eV and 2.0 × 10<sup>-3</sup> S cm<sup>-1</sup> respectively. The conductivity could be increased to 1.5 × 10<sup>-1</sup> S cm<sup>-1</sup> with potassium doping in K<sub>0.1</sub>Ba<sub>1.9</sub>Zn<sub>1-<i>x</i></sub> O<sub>2-<i>x</i></sub> Cu<sub>2</sub>Se<sub>2</sub>. Hall measurements confirmed that both materials were p-type conductors with holes as the dominant charge carriers.","dates":{"release":"2024-01-01T00:00:00Z","publication":"2024 Nov","modification":"2026-05-29T09:31:57.177Z","creation":"2025-04-04T22:47:51.55Z"},"accession":"S-EPMC11440232","cross_references":{"pubmed":["39360290"],"doi":["10.1039/d4tc02458c"]}}