Researchers from Chung-Ang University, Gwangju Institute of Science and Technology, Hanyang University, The University of Electro-Communications and Chungbuk National University have reported that introducing 4-Phenylthiosemicarbazide (4PTSC) as an additive during the production of tin halide perovskites (Sn-HPs) can boost the performance of perovskite solar cells (PSCs).
Through extensive analyses and experimental comparisons between regular Sn-HP PSCs and those containing the proposed additive, the researchers showcased the multiple functionalities of 4PTSC as an additive. "We purposely chose a multifunctional molecule that acts as a coordination complex and a reducing agent, passivates defect formation, and improves stability," explains Associate Professor Dong-Won Kang from Chung-Ang University, who led the study.
Since 4PTSC functions as a coordinating ligand, it can effectively regulate the process of crystal growth. On the one hand, the π-conjugated phenyl ring in the 4PTSC molecule promotes preferred crystal growth orientation, minimizing the formation of defects. Interestingly, 4PTSC also passivates any defects that do form through the chemical coordination of 4PTSC and SnI2. In turn, this shields the perovskite surface and prevents uncoordinated Sn2+ and halide ions from participating in unwanted reactions. What's more, the NH2 nucleophilic sites in 4PTSC further hinder SnI2 oxidation and ion migration, improving the stability of the PSCs.
Thanks to this additive, the researchers were able to produce PSCs with unprecedented performance. "The 4PTSC-modified devices achieved a peak efficiency of 12.22% with an enhanced open-circuit voltage of 0.94 V and exhibited superior long-term stability, retaining almost 100% of the initial power conversion efficiency, even after 500 h and about 80% after 1200 h in ambient conditions without any encapsulation. This is different from the marked degradation observed in control devices within the first 300 h," highlights Kang.
Given that Sn-HPs are relatively inexpensive to manufacture and demonstrate good performance and great durability, this study could pave the way to more accessible and long-lasting solar panels. This can help in making energy cheaper for the general population while staying in line with current sustainability goals. "Addressing the key challenges of Sn-HPs and significantly improving their performance aligns with our goal of contributing to developing efficient and sustainable renewable energy solutions, thereby advancing green technologies and promoting a sustainable future," concludes Kang.
