CZTSSe為一種具有潛力的光電材料，與現今CIGS薄膜太陽能電池相比，有其組成元素含量豐富且易取得，並且無毒對環境傷害不高，符合環保需求。
本研究之主旨係使用濺鍍法來獲得穩定的前驅物薄膜而後經由硒化退火形成銅鋅錫硫硒(CZTSSe)薄膜太陽能電池之吸收層。研究中嘗試不同比例之銅鋅錫硫硒合金靶來製備前驅物，接著硒化成吸收層，首先利用SEM、XRD來確認退火參數對於薄膜品質之影響，再經由Raman，霍爾量測來確定薄膜的特性，最終使用IV measurement儀器來量測太陽能電池元件效率，了解其光電特性。
本研究發現，由於使用濺鍍法製備前驅物，退火對於元素成分比例改動並無明顯影響，發現其銅比例不可太高，否則容易在表面形成銅二次項，並經由表面處理後，會使薄膜出現孔洞。
此外退火參數會影響晶粒的生長，從一開始的合金前驅物，可利用快升溫達到目標溫度持溫一段時間，使得薄膜反應完全，此方式比起緩慢升溫方式，除了降低製程需時，也可避免長時間退火，導致元素硒流失，降低薄膜品質。
最後，我們在前驅物銅鋅錫硒合金經以每分鐘30度之升溫速率達到500度時持溫15分的硒化退火，並緩慢冷卻至室溫可得到品質較高吸收層薄膜。並經由後製程優化提高其短路電流，最終製成之薄膜太陽能電池具有開路電壓為0.1mV，短路電流為20.62mA/cm2，填充因子為52.64%，其效率可達1.08%。

關鍵字:銅鋅錫硫硒、硒化、四元靶材

SUMMARY
In this Study, CZTS and CZTSSe films were prepared by sputtering as the absorption layer, we can find that the selection of the target composition ratio is very important for the subsequent preparation of the absorption layer. Because the copper-rich problem (Cu-rich) cannot be solved by annealing which lead to the efficiency of device was only 0.44%.
We adjusted the target ratio and reduced the five-element material to the four-element material, in order to lessen the influence of changes between elements, and then try variety of annealing methods to explore the influence of the heating rate and holding time on the absorption layer, and finally we use high heating rate (30°C/min) and holding the temperature for 15 minutes to prepare a compact and non-porous absorber layer.
Finally, we successfully fabricated a device with an efficiency of 0.53%, and the short-circuit current JSC was optimized from the original 16.15 mA/cm2 increased to 20.62 mA/cm2, and the efficiency can reach to 1.08%.

Keywords: Cu2ZnSn(S,Se)4(CZTSSe), quaternary target, sputtering, selenization

1. Fella, C.M., Y.E. Romanyuk, and A.N. Tiwari, Technological status of Cu2ZnSn(S,Se)4 thin film solar cells., Solar Energy Materials and Solar Cells, 119: p. 276-277., 2013.
2. Kamoun, N., H. Bouzouita, and B. Rezig, Fabrication and characterization of Cu2ZnSnS4 thin films deposited by spray pyrolysis technique., Thin Solid Films, 515(15): p. 5949-5952., 2007.
3. Tanaka, K., N. Moritake, and H. Uchiki, Preparation of Cu2ZnSnS4 thin films by sulfurizing sol–gel deposited precursors., Solar Energy Materials and Solar Cells, 91(13): p. 1199-1201., 2007.
4. Zoppi, G., et al., Cu2ZnSnSe4thin film solar cells produced by selenisation of magnetron sputtered precursors., Progress in Photovoltaics: Research and Applications., 17(5): p. 315-319., 2009
5. Repins, I., et al., Co-evaporated Cu2ZnSnSe4 films and devices., Solar Energy Materials and Solar Cells., 101: p. 154-159., 2012
6. Mkawi, E.M., et al., Substrate temperature effect during the deposition of (Cu/Sn/Cu/Zn) stacked precursor CZTS thin film deposited by electron-beam evaporation., Journal of Materials Science: Materials in Electronics., 29(23): p. 20476-20484., 2018.
7. Gruning, M., A. Marini, and A. Rubio, Density functionals from many-body perturbation theory: the band gap for semiconductors and insulators., J Chem Phys., 124(15): p. 154108. , 2006.
8. Maeda, T., S. Nakamura, and T. Wada, First-principles calculations of vacancy formation in In-free photovoltaic semiconductor Cu2ZnSnSe4., Thin Solid Films, 519(21): p. 7513-7516., 2011.
9. Pawar, S.M., et al., Fabrication of Cu2ZnSn(SxSe1−x)4 thin film solar cell by single step sulfo-selenization of stacked metallic precursors., Current Applied Physics, 15(2): p. 59-63. , 2015.
10. Chen, S., et al., Electronic structure and stability of quaternary chalcogenide semiconductors derived from cation cross-substitution of II-VI andI-III-VI2compounds., Physical Review B., 79(16)., 2009.
11. Chen, S., et al., Defect physics of the kesterite thin-film solar cell absorber Cu2ZnSnS4., Applied Physics Letters, 96(2)., 2010.
12. Chen, S., et al., Classification of lattice defects in the kesterite Cu2ZnSnS4 and Cu2ZnSnSe4 earth-abundant solar cell absorbers., Adv Mater ,25(11): p. 1522-39., 2013.
13. Tanaka, T., et al., Existence and removal of Cu2Se second phase in coevaporated Cu2ZnSnSe4thin films. Journal of Applied Physics, 2012. 111(5).
14. Olgar, M.A., et al., Influence of copper composition and reaction temperature on the properties of CZTSe thin films., Journal of Alloys and Compounds., 682: p. 610-617., 2016.
15. Babu, G., et al., Effect of Cu/(Zn+Sn) ratio on the properties of co-evaporated Cu2ZnSnSe4 thin films., Solar Energy Materials and Solar Cells - SOLAR ENERG MATER SOLAR CELLS., 94: p. 221-226., 2010.
16. Tanaka, T., et al., Existence and removal of Cu2Se second phase in coevaporated Cu2ZnSnSe4 thin films., Journal of Applied Physics., 111. , 2012.
17. Ren, Y., et al., Investigation of the SnS/Cu2ZnSnS4 Interfaces in Kesterite Thin-Film Solar Cells., ACS Energy Letters., 2(5): p. 976-981., 2017.
18. Vauche, L., et al., Detrimental effect of Sn-rich secondary phases on Cu2ZnSnSe4 based solar cells., Journal of Renewable and Sustainable Energy., 8: p. 033502., 2016.
19. Stanchik, A.V., et al., Effects of selenization time and temperature on the growth of Cu2ZnSnSe4 thin films on a metal substrate for flexible solar cells., Solar Energy., 178: p. 142-149., 2019.
20. Temgoua, S., et al., Effects of SnSe 2 secondary phases on the efficiency of Cu 2 ZnSn(S x ,Se 1−x ) 4 based solar cells., Thin Solid Films., 582: p. 215-219., 2015.
21. Fairbrother, A., et al., Secondary phase formation in Zn-rich Cu2ZnSnSe4-based solar cells annealed in low pressure and temperature conditions., Progress in Photovoltaics: Research and Applications., 22(4): p. 479-487., 2014.
22. Hsu, W.-C., et al., The effect of Zn excess on kesterite solar cells., Solar Energy Materials and Solar Cells., 113: p. 160-164., 2013.
23. Kim, Y.-C., et al., The effect of S/(S+Se) ratios on the formation of secondary phases in the band gap graded Cu2ZnSn(S,Se)4 thin film solar cells., Journal of Alloys and Compounds., 793: p. 289-294., 2019.
24. Liu, C.-Y., et al., Sodium Passivation of the Grain Boundaries in CuInSe2 and Cu2ZnSnS4 for High-Efficiency Solar Cells., Advanced Energy Materials., 7(8)., 2017.
25. Gershon, T., et al., The Role of Sodium as a Surfactant and Suppressor of Non-Radiative Recombination at Internal Surfaces in Cu2ZnSnS4., Advanced Energy Materials., 5(2)., 2015.
26. Ishizuka, S., et al., Fabrication of wide-gap Cu(In1−xGax)Se2 thin film solar cells: a study on the correlation of cell performance with highly resistive i-ZnO layer thickness., Solar Energy Materials and Solar Cells., 87(1-4): p. 541-548., 2005.
27. Fairbrother, A., et al., Development of a selective chemical etch to improve the conversion efficiency of Zn-rich Cu2ZnSnS4 solar cells., J Am Chem Soc., 134(19): p. 8018-21., 2012.
28. Bär, M., et al., Impact of KCN etching on the chemical and electronic surface structure of Cu2ZnSnS4 thin-film solar cell absorbers., Applied Physics Letters., 99(15)., 2011.
29. Zhu, Y., et al., Direct current magnetron sputtered Cu2ZnSnS4 thin films using a ceramic quaternary target., Journal of Alloys and Compounds., 727: p. 1115-1125., 2017.
30. Walsh, A., et al., Kesterite Thin-Film Solar Cells: Advances in Materials Modelling of Cu2ZnSnS4., Advanced Energy Materials., 2(4): p. 400-409., 2012.
31. Bishop, D.M., et al., Modification of defects and potential fluctuations in slow-cooled and quenched Cu2ZnSnSe4 single crystals., Journal of Applied Physics., 121(6)., 2017.
32. Kim, K.-H. and I. Amal, Growth of Cu2ZnSnSe4 thin films by selenization of sputtered single-layered Cu-Zn-Sn metallic precursors from a Cu-Zn-Sn alloy target., Electronic Materials Letters., 7(3): p. 225., 2011.