Advancements in photovoltaic efficiency: The role of fluorine-doped CZTS in homojunction solar cells

Milad Yousefizad; Zohreh Golshan Bafghi; Amirmohammad Shahriyari; Andia Javanmardi; Naser Hakimi Raad; Ashraf Ahmadi Shadmehri; Siavosh Samoodi; Negin Manavizadeh; Ali Moafi

doi:10.1016/j.heliyon.2025.e42300

Advancements in photovoltaic efficiency: The role of fluorine-doped CZTS in homojunction solar cells

Heliyon. 2025 Jan 27;11(3):e42300. doi: 10.1016/j.heliyon.2025.e42300. eCollection 2025 Feb 15.

Authors

Milad Yousefizad¹, Zohreh Golshan Bafghi¹, Amirmohammad Shahriyari¹, Andia Javanmardi¹, Naser Hakimi Raad¹, Ashraf Ahmadi Shadmehri², Siavosh Samoodi³, Negin Manavizadeh^{1

4}, Ali Moafi²

Affiliations

¹ Nanostuctued-Electronic Devices Laboratory, Faculty of Electrical Engineering, K. N. Toosi University of Technology, 163171419 Tehran, Iran.
² Physics and Energy Engineering Faculty, Amirkabir University of Technology, Tehran, Iran.
³ Department of Mechanical Engineering, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
⁴ Materonics and Materionics Research Group, K. N. Toosi University of Technology, Tehran, Iran.

Abstract

Copper Zinc Tin Sulfide (CZTS) solar cells have absorbed significant appeal as an efficient approach for sustainable photovoltaic technology. This research introduces a groundbreaking approach to thin-film solar cells using a novel Fluorine-doped CZTS composition with a new device configuration. The DFT calculations indicate that F atoms prefer Cu sites and maintain a direct band gap in CZTS, promoting n-type conductivity. Optical studies demonstrate that F-doping enhances conductivity, refractive index, and light absorption through the visible spectrum. Furthermore, the performance of CZTS-based cells in both heterojunction and homojunction configurations is under investigation. The homojunction configuration with Al:ZnO intermediate layer enhances V_OC and J_SC compared to conventional heterojunction structures. The J_SC and V_OC of homojunction solar cells with AZO layer are 24.74 mAcm^-2 and 0.94 V, respectively. The efficiency of the solar cell is optimized considering the thickness of the p-CZTS layer, which saturates at 21.8 % beyond 5 μm thickness. At the beginning of near-infrared wavelengths, the homojunction structure effectively absorbs light. Combining F-doped CZTS and homojunction configuration with a ZnO and AZO intermediate layer demonstrates superior performance due to reduced carrier recombination and enhanced photogeneration. The novel homojunction design advances CZTS-based technology, achieving impressive effectiveness using environmentally friendly materials.

Keywords: CZTS solar cell; Efficiency improvement; Fluorine doping; Homojunction architecture solar cell; Light absorption enhancement.