Zahida Malik, Sarah Broadley, Sebastian J. C. Herkelrath, Daniel W. Newbrook, Liam Kemp, George Rutt, Zoltán A. Gál, Jack N. Blandy, Joke Hadermann, Daniel W. Davies, Robert D. Smyth, David O. Scanlon, Ruomeng Huang, Simon J. Clarke and Geoffrey Hyett
{"title":"Observation and enhancement through alkali metal doping of p-type conductivity in the layered oxyselenides Sr2ZnO2Cu2Se2 and Ba2Zn1−xO2−xCu2Se2†","authors":"Zahida Malik, Sarah Broadley, Sebastian J. C. Herkelrath, Daniel W. Newbrook, Liam Kemp, George Rutt, Zoltán A. Gál, Jack N. Blandy, Joke Hadermann, Daniel W. Davies, Robert D. Smyth, David O. Scanlon, Ruomeng Huang, Simon J. Clarke and Geoffrey Hyett","doi":"10.1039/D4TC02458C","DOIUrl":null,"url":null,"abstract":"<p >The optoelectronic properties of two layered copper oxyselenide compounds, with nominal composition Sr<small><sub>2</sub></small>ZnO<small><sub>2</sub></small>Cu<small><sub>2</sub></small>Se<small><sub>2</sub></small> and Ba<small><sub>2</sub></small>ZnO<small><sub>2</sub></small>Cu<small><sub>2</sub></small>Se<small><sub>2</sub></small>, 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<small><sub>2</sub></small>ZnO<small><sub>2</sub></small>Cu<small><sub>2</sub></small>Se<small><sub>2</sub></small>, adopts the expected tetragonal <em>Sr</em><small><sub><em>2</em></sub></small><em>Mn</em><small><sub><em>3</em></sub></small><em>SbO</em><small><sub><em>2</em></sub></small> structure with <em>I</em>4/<em>mmm</em> symmetry, and has a band gap of 2.16 eV, and a room temperature conductivity of 4.8 × 10<small><sup>−1</sup></small> S cm<small><sup>−1</sup></small>. The conductivity of the compound could be increased to 4.2 S cm<small><sup>−1</sup></small> when sodium doped to a nominal composition of Na<small><sub>0.1</sub></small>Sr<small><sub>1.9</sub></small>ZnO<small><sub>2</sub></small>Cu<small><sub>2</sub></small>Se<small><sub>2</sub></small>. In contrast, the barium containing material was found to have a small zinc oxide deficiency, with a sample dependent compositional range of Ba<small><sub>2</sub></small>Zn<small><sub>1−<em>x</em></sub></small>O<small><sub>2−<em>x</em></sub></small>Cu<small><sub>2</sub></small>Se<small><sub>2</sub></small> where 0.01 < <em>x</em> < 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 <em>I</em>4/<em>mmm</em> 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<small><sub>2</sub></small>Zn<small><sub>1−<em>x</em></sub></small>O<small><sub>2−<em>x</em></sub></small>Cu<small><sub>2</sub></small>Se<small><sub>2</sub></small> does not adopt a long range ordered arrangement, but also that the idealised <em>I</em>4/<em>mmm</em> 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<small><sub>2</sub></small>Zn<small><sub>1−<em>x</em></sub></small>O<small><sub>2−<em>x</em></sub></small>Cu<small><sub>2</sub></small>Se<small><sub>2</sub></small> were determined to be 2.22 eV and 2.0 × 10<small><sup>−3</sup></small> S cm<small><sup>−1</sup></small> respectively. The conductivity could be increased to 1.5 × 10<small><sup>−1</sup></small> S cm<small><sup>−1</sup></small> with potassium doping in K<small><sub>0.1</sub></small>Ba<small><sub>1.9</sub></small>Zn<small><sub>1−<em>x</em></sub></small>O<small><sub>2−<em>x</em></sub></small>Cu<small><sub>2</sub></small>Se<small><sub>2</sub></small>. Hall measurements confirmed that both materials were p-type conductors with holes as the dominant charge carriers.</p>","PeriodicalId":84,"journal":{"name":"Journal of Materials Chemistry C","volume":" 43","pages":" 17574-17586"},"PeriodicalIF":5.7000,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11440232/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Materials Chemistry C","FirstCategoryId":"1","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2024/tc/d4tc02458c","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The optoelectronic properties of two layered copper oxyselenide compounds, with nominal composition Sr2ZnO2Cu2Se2 and Ba2ZnO2Cu2Se2, 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, Sr2ZnO2Cu2Se2, adopts the expected tetragonal Sr2Mn3SbO2 structure with I4/mmm symmetry, and has a band gap of 2.16 eV, and a room temperature conductivity of 4.8 × 10−1 S cm−1. The conductivity of the compound could be increased to 4.2 S cm−1 when sodium doped to a nominal composition of Na0.1Sr1.9ZnO2Cu2Se2. In contrast, the barium containing material was found to have a small zinc oxide deficiency, with a sample dependent compositional range of Ba2Zn1−xO2−xCu2Se2 where 0.01 < x < 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 I4/mmm 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 Ba2Zn1−xO2−xCu2Se2 does not adopt a long range ordered arrangement, but also that the idealised I4/mmm structure with an unsplit oxide site was not consistent with the extra reflections observed in the electron diffractograms. The band gap and conductivity of Ba2Zn1−xO2−xCu2Se2 were determined to be 2.22 eV and 2.0 × 10−3 S cm−1 respectively. The conductivity could be increased to 1.5 × 10−1 S cm−1 with potassium doping in K0.1Ba1.9Zn1−xO2−xCu2Se2. Hall measurements confirmed that both materials were p-type conductors with holes as the dominant charge carriers.
期刊介绍:
The Journal of Materials Chemistry is divided into three distinct sections, A, B, and C, each catering to specific applications of the materials under study:
Journal of Materials Chemistry A focuses primarily on materials intended for applications in energy and sustainability.
Journal of Materials Chemistry B specializes in materials designed for applications in biology and medicine.
Journal of Materials Chemistry C is dedicated to materials suitable for applications in optical, magnetic, and electronic devices.
Example topic areas within the scope of Journal of Materials Chemistry C are listed below. This list is neither exhaustive nor exclusive.
Bioelectronics
Conductors
Detectors
Dielectrics
Displays
Ferroelectrics
Lasers
LEDs
Lighting
Liquid crystals
Memory
Metamaterials
Multiferroics
Photonics
Photovoltaics
Semiconductors
Sensors
Single molecule conductors
Spintronics
Superconductors
Thermoelectrics
Topological insulators
Transistors