A new approach for alkali incorporation in Cu2ZnSnS4 solar cells

被引：7

作者：

Valdes, M. ^{[1
]}

Hernandez, A. ^{[2
]}

Sanchez, Y. ^{[2
]}

Fonoll, R. ^{[2
]}

Placidi, M. ^{[2
,3
]}

Izquierdo, V ^{[2
]}

Cabas-Vidani, A. ^{[4
]}

Valentini, M. ^{[5
]}

Mittiga, A. ^{[5
]}

Pistor, P. ^{[6
]}

Malerba, C. ^{[5
]}

Saucedo, E. ^{[3
]}

机构：

[1] CONICET UNMdP, Inst Invest Ciencia & Tecnol Mat INTEMA, Av Cristobal Colon 10850,B7606WV, Mar Del Plata, Buenos Aires, Argentina

[2] Catalonia Inst Energy Res IREC, Barcelona 08930, Spain

[3] Polytech Univ Catalonia UPC, Elect Engn Dept, Campus Besos,Av dEduard Maristany 16, Barcelona 08930, Spain

[4] Empa Swiss Fed Labs Mat Sci & Technol, Lab Thin Films & Photovolta, Ueberlandstr 129, CH-8600 Dubendorf, Switzerland

[5] ENEA, Casaccia Res Ctr, Via Anguillarese 301, I-00123 Rome, Italy

[6] Univ Pablo de Olavide, Phys Chem Sect, Ctra Utrera 1, Seville 41013, Spain

来源：

JOURNAL OF PHYSICS-ENERGY | 2022年 / 4卷 / 04期

基金：

欧盟地平线“2020”;

关键词：

kesterite; CZTS; alkali doping; CBD; PDA; thin film photovoltaics; THIN-FILMS; EFFICIENCY; SULFURIZATION; IMPACT;

D O I：

10.1088/2515-7655/ac96a4

中图分类号：

TE [石油、天然气工业]; TK [能源与动力工程];

学科分类号：

0807 ; 0820 ;

摘要：

The addition of alkali elements has become mandatory for boosting solar cell performance in chalcogenide thin films based on kesterites (Cu2ZnSnS4, CZTS). A novel doping process is presented here, that consists in the incorporation of sodium or lithium during the deposition of the CdS buffer layer, followed by a post-deposition annealing (PDA). As the doping route leads to more efficient devices in comparison with the undoped reference sample, the influence of PDA temperature was also investigated. Compositional profiling techniques, time-of-flight secondary ion mass spectrometry (TOF-SIMS) and glow discharge optical mission spectroscopy (GDOES), revealed a dependence of the alkaline distribution in kesterites with the PDA temperature. Although the doping process is effective in that it increases the alkaline concentration compared to the undoped sample, the compositional profiles indicate that a significant proportion of Li and Na remains 'trapped' within the CdS layer. In the 200 degrees C-300 degrees C range the alkali profiles registered the higher concentration inside the kesterite. Despite this, an additional alkali accumulation close to the molybdenum/fluorine doped tin oxide substrate was found for all the samples, which is frequently related to alkali segregation at interfaces. The addition of both, lithium and sodium, improves the photovoltaic response compared to the undoped reference device. This is mainly explained by a substantial improvement in the open-circuit potential (V (oc)) of the cells, with best devices achieving efficiencies of 4.5% and 3% for lithium and sodium, respectively. Scanning-electron microscopy images depicted a 'bilayer structure' with larger grains at the top and small grains at the bottom in all samples. Moreover, the calculated bandgap energies of the CZTS films account for changes in the crystallographic order-disorder of the kesterites, more related to the PDA treatment rather than alkali incorporation. Even if further optimization of the absorber synthesis and doping process will be required, this investigation allowed the evaluation of a novel strategy for alkali incorporation in kesterite based solar cells.

引用

页数：12