Urea–acetamide-based deep eutectic compound as novel, eco-friendly additives in stable and efficient dye-sensitized solar cells: A performance and electrochemical study

• Published in: Electrochimica acta 2024-05, Vol.487, p.144156, Article 144156
• Main Authors: Nguyen, De, Hoang, Van Ha, Ngo, Phuong Ha Thi, Vo, Tho Anh Ngoc, Nguyen, Thuy Thanh Doan, Nguyen, Phuong Tuyet
• Format: Article
• Language: English
• Subjects: Acetamide; Deep eutectic solvent; Dye-sensitized solar cells; Electrolyte additives; Urea
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2024.144156

Deep eutectic solvents of urea and acetamide at molar ratios of 1:1 (UA11) and 1:2 (UA12) were investigated as new, eco-friendly, and effective electrolyte additive candidates to replace the commonly used 4‑tert-butylpyridine additive in dye-sensitized solar cells (DSCs). Both UA11 and UA12 resulted in a high open circuit potential (VOC) of about 745 mV, which was very competitive to a VOC of 754 mV from DSCs using 4‑tert-butylpyridine (4-TBP). After 2240 h of storage, performance dropped 8% in devices using UA11 compared to about 25% of devices using 4-TBP as an additive. Our time-series data analysis revealed the correlation between the short circuit current (JSC) drop and the increase of counter-electrode resistance. In addition, by examining the VOC correlation between working electrode resistance and working electrode capacitance in four electrolyte groups (NAd, UA11, UA12, 4-TBP), we could speculate the effects of the DES urea-acetamide as well as 4-TBP. 4-TBP could improve the VOC by adsorption to the bare TiO2 surface and diminish the recombination reaction. On the other hand, 4-TBP could interact with iodine species in the electrolyte solution to minimize the current leakage from the TiO2 surface to the iodine species. In the case of UA11 and UA12, the additive seemed to interact with the iodine species only.