Effect of K Doping on the Performance of Aqueous Solution‐Processed Cu(In,Ga)Se2 Solar Cell

• Published in: Advanced energy and sustainability research 2022-07, Vol.3 (7), p.n/a
• Main Authors: Hao, Shasha, Yu, Shaotang, Liu, Xinge, Li, Bingyan, Han, Shuaiqi, Xin, Hao, Yan, Weibo, Huang, Wei
• Format: Article
• Language: English
• Subjects: Aqueous solutions; chalcopyrite; Copper; Copper indium gallium selenides; Diffraction; Doping; Efficiency; Energy gap; Evaporation; Gallium; Grain growth; Investigations; K doping; Magnesium fluorides; Magnetron sputtering; Morphology; Nitrates; Nonuniformity; Photovoltaic cells; Precursors; Production costs; Selenide; Selenium; Solar cells; Solvents; Spectrum analysis; Vacuum thermal evaporation
• ISSN: 2699-9412; 2699-9412
• DOI: 10.1002/aesr.202200006

Copper indium gallium selenide Cu(In,Ga)Se2 (CIGS) solar cells fabricated by vacuum thermal evaporation, magnetron sputtering, or organic solvent solution‐process either lead to high manufacturing cost and film nonuniformity or cause explosion, toxication and pollution. To address these issues, herein, water as a solvent to prepare the CIGS precursor solution is used and 7.04% efficient CIGS solar cells without MgF2 antireflection layer is obtained. Furthermore, for the first time, K doping on CIGS films via adding “K+” into the aqueous precursor solution is conducted. K–In–Se species is formed in the process of selenization and acts as a Se reservoir during CIGS grain growth, resulting in improved quality of the CIGS film with much larger grains. K doping can also inhibit the loss of Ga element. The high‐bandgap K–In–Se phase and higher Ga content combine to result in the increase in the CIGS bandgap. As a result, the K‐doped CIGS solar cell achieves a 33.1% enhancement in efficiency to 9.37%, with the significant increase in the open‐circuit voltage from 520.5 to 597.1 mV and fill factor from 50.77 to 55.36%. These results provide an important preliminary foundation for the development of aqueous precursor solution‐based CIGS solar cells. A “K+”‐containing precursor aqueous solution for Cu(In,Ga)Se2 (CIGS) is first prepared, from which the K‐doped CIGS absorber film with higher quality is fabricated, due to the formation of K–In–Se acting as the Se reservoir to promote the growth of CIGS grain. Consequently, the K‐doped CIGS film‐based solar cell achieves a 33.1% enhancement of efficiency from 7.04 to 9.37%.