Room-Temperature Synthesized SnO2 Quantum Dots as an Efficient Charge Transport Layer for Scalable Perovskite Photovoltaics

Abraha Gidey^a, Elnaz Rad^a, Katherine Latosinsky^a, Sunil Suresh^a^,^b^,^c^,^d, Alexander Uhl^a

^aLaboratory for Solar Energy & Fuels (LSEF), School of Engineering, The University of British Columbia, Kelowna V1V 1V7, Canada

^bThin Film PV Technology, Imec, imo-imomec, Thor Park 8320, Genk, 3600, Belgium

^cUHASSELT, Institute for Materials Research (IUMAT), Hasselt, Belgium.

^dEnergyVille, IUMAT, Genk, Belgium.

Proceedings of MATSUS Fall 2026 Conference (MATSUSFall26)

D2 Functional Materials for Emerging Photovoltaics: from Everyday Integration to Extreme Environments

Palma, Spain, 2026 October 26th - 30th

Organizers: Jessica Barichello, Stefania Cacovich and Fabio Matteocci

Oral, Abraha Gidey, presentation 096
Publication date: 22nd July 2026

Quantum dots (QDs) are a subject of great interest in the domains of materials science, spectroscopy, sensors, biological imaging, diagnostics, and photovoltaics. SnO₂ QDs have garnered significant attention as Electron Transport Layer (ETLs) in Perovskite Photovoltaicsdue to their exceptional optoelectronic properties, such as a wide bandgap, good electron mobility, high thermal stability, and compatibility with solution processing techniques. Despite the advancements in replacing conventional SnO₂with SnO₂ QDs, current synthesis strategies are complex and rely on hazardous facilitators such as thiourea, raising concerns regarding environmental impact alongside long-term device stability. To address these issues, we report a room-temperature, ink-based approach for synthesizing ultra-small SnO₂QDs under ambient conditions, employing environmentally benign ligands. We explore the influence of ligand methylation on the properties and performance of the SnO₂ QD inks and thin films, and analyze the chemical, morphological, crystallographic, electronic, and optoelectronic characteristics of SnO₂QD thin films to optimize precursor formulation for depositing phase-pure SnO₂ QDs. Our optimized urea-based SnO₂QDs deliver device PCEs of over 20%, outperforming conventional thiourea-derived SnO₂ QDs. Furthermore, our devices retained ~90% of their initial efficiency after 90 days in a dry box and over 93% under 72 hours of continuous ambient illumination, compared to ~83% and 90% retention, respectively, for thiourea-based reference devices. This novel approach may offer a pathway to stable, highly efficient, and flexible photovoltaic cells via low-temperature processing.

References:

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[2] Cheng, Y.; Wang, S.; Zhou, L.; Chang, L.; Liu, W.; Yin, D.; Yi, Z.; Wang, L. SnO2 Quantum Dots: Rational Design to Achieve Highly Reversible Conversion Reaction and Stable Capacities for Lithium and Sodium Storage. Small 2020, 16, 2000681.

[3] Kim, W.; Kim, J.; Kim, D.; Koo, B.; Yu, S.; Li, Y.; Kim, Y.; Ko, M. J. Completely Annealing-Free Flexible Perovskite Quantum Dot Solar Cells Employing UV-Sintered Ga-Doped SnO2 Electron Transport Layers. npj Flexible Electronics 2024, 8, 20.

[4] Ren, Z.; Liu, K.; Hu, H.; Guo, X.; Gao, Y.; Fong, P. W. K.; Liang, Q.; Tang, H.; Huang, J.; Zhang, H.; et al. Room-Temperature Multiple Ligands-Tailored SnO2 Quantum Dots Endow in Situ Dual-Interface Binding for Upscaling Efficient Perovskite Photovoltaics with High V OC. Light Sci. Appl. 2021, 10, 239

[5] Yang, G.; Chen, C.; Yao, F.; Chen, Z.; Zhang, Q.; Zheng, X.; Ma, J.; Lei, H.; Qin, P.; Xiong, L.; Ke, W.; Li, G.; Yan, Y.; Fang, G. Effective Carrier-Concentration Tuning of SnO2 Quantum Dot Electron-Selective Layers for High-Performance Planar Perovskite Solar Cells. Advanced Materials 2018, 30, 1706023

Acknowledgements:

The authors acknowledge that this work was conducted on the traditional, ancestral, and unceded territory of the Syilx Okanagan Nation (Kelowna). A.G., E.G, K.L., and A.R.U. acknowledge the financial support provided by Solaires Entreprises Inc., MITACS, the Natural Sciences and Engineering Research Council of Canada (NSERC), and Canada Foundation for Innovation (CFI) and British Columbia Knowledge Development Fund (BCKDF), through grants BC-ISED IT26569, RGPIN-2019-05489, I2IPJ 586910 - 23, and 39081 and 42549, respectively. A.R.U. further acknowledges financial support from the Alexander von Humboldt Foundation. S.S. also acknowledges funding received from the innovation program under the Marie Skłodowska-Curie grant agreement No. 101208369. The authors also acknowledge 4D LABS at Simon Fraser University, supported by CFI and BCKDF, and Pacific Economic Development Canada (PacifiCan), for conducting the XPS and TEM sample analyses. The authors acknowledge Ahmed G. Mahmoud for his support with graphical improvements.

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