第32卷第1期 2017年1月
Article ID: 1000-324X(2017)01-0101-06
无机材料学报 Jourmal of Inorganic Materials
VoL.32 No. 1 Jan.,2017
DOI:10.15541/jim20160210
SynthesisandPhysical Properties of SolarMaterialCui-Li,InSe2
HUANG Rong-Tiel-2, ZHENG Ming", SUI Li-Fang’-2, CAI Chuan-Bing', HUANG Fu-Qiang?3(1. Department of Physics, Shanghai University, Shanghai 200444, China; 2. CAS Key Laboratory of Materials for Energy Conver sion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China; 3. Beijing National Laboratory for Molecular Sciences and State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Mo-lecular Engineering, Peking University, Beijing 100871, China)
eeeessea (seae sealed quartz tubes at 873 K. To understand the physical properties of the materials, the structural, electrical and opti-cal properties were systematically investigated. After doping with lithium, the samples crystallize in chalcopyrite structure with large grain sizes. Electrical resistivity and optical band gap of Li-doped Cu,,Li,InSe2 are greatly en-hanced to 2.7310* 0-cm and 1.33 eV from original values of 1.98x10° -cm and 0.9 eV, respectively. The large band gap improves the open circuit voltage, indicating that the Li-doping CulnSe could be a promising material to future photovoltaic applications.
Key words: chalcopyrite structure; solar cell; bulk material; physical properties; CulnSe2
CulnSe2 (CIS) as a promising candidate for thin film semiconductor solar cells has high absorption coefficient(~10° cm"'). Although its optical band gap (1.04 eV) is lower than the optimal gap of~1.5 evil, the corresponding photovoltaic cells can reach the highest efficiency of 20.3%[2], CulnSe2 and its derivatives have been extensively studied recently/3, however, the previous works were mainly focused on thin films and nanostructures to enhance the photovoltaic behaviors(46], On the other hand, the physical properties of the bulk materials are crucial to ex-plore the intrinsic features, and only few studies concen-trated on the physical properties of the bulk materials[7]
Many studies have shown that the electronic band structure can be changed by doping to improve the energy conversion efficiencyl8)], The band gap of CulnSez in-creases to 1.2 eV with 30% Ga doping at In site to form Culn-Ga,Se2 (CIGS) alloy, resulting in the increase of the open circuit voltage of the device. However, the short cir-cuit current decreases largely, and the cell efficiency drops off when x > 0.3(9], It has been observed that Na-doping in the CIS films leads to larger grain sizes, which can reduce boundary scattering and thus increase the carrier mobilityliol, Nevertheless, binary phase would be found on high Na concentrations, and thus decrease the cell effi-ciencyl), After doping with lithium, the band gap may be improved to increase the open circuit voltage because of
larger band gap of LilnSe2 (2.85 eVy)12) compared to that of CulnSe2 (1.04 eV). LiSe is an effective flux for grains growth in many syntheses, which can act not only as a reactant but also a solvent(13], The increase of electrical resistivity may reduce the loss of current by avoiding the recombination of e-h at the high carrier concentration. Consequently, it is possible to improve the solar cell per-formancebylithiumdoping
Generally speaking, the physical properties of the Cu-InSe and its derivatives are quite sensitive to the prepara-tion conditions, and many methods have been developed to fabricate the bulk materials. The present study mainly focuses on the relationship between the structural and physical properties of the Li-doped Cu-Li,InSe2 (x = 00.4) bulk material. In this study, the Li-doped samples were prepared by solid state reaction in a relatively low temperature (873 K) than the reported reaction tempera-fures (12731423 K)(1415], And the crystal structure, elec-trical resistivity and optical characteristics are investigated to understand the improvement of photoelectrical per-formance.
Experimental
1.1
Sample preparation
The following reagents were used as obtained: Cu (Al-
Received dste: 2016-03-31; Modified date: 2016-05-09
Foundatien item: National Natural Science Foundation of China (61376056, 51402341); Science and Technology Commission of
Shanghai (13JC1405700, 14520722000); Key Research Program of Chinese Academy of Sciences (KGZD-EW-T06)
Biography: HUANG Rong-Tie (1988), male, candidate of master degrce. E-mail: huangrongtiestudent.sic.ac.cn
Corresponding author: HUANG Fu-Qiang,professor. E-mail: huangfqmailsic.ac.cn 万方数据