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Topic

Strategies for improving the performance of single-crystal perovskite solar cells

Department of Chemistry

Date & location

• Friday, April 10, 2026
• 9:00 A.M.
• Elliott Building, Room 305

Examining Committee

Supervisory Committee

• Dr. Makhsud Saidaminov, Department of Chemistry, ̽��ϵ�� (Supervisor)
• Dr. Alexandre Brolo, Department of Chemistry, UVic (Member)
• Dr. Magdalena Bazalova-Carter, Department of Physics and Astronomy, UVic (Outside Member)

External Examiner

• Dr. Liberato Manna, Department of Nanochemistry, Instituto Italiano di Technologia

Chair of Oral Examination

• Dr. Marco Cozzi, Department of Economics, UVic

Abstract

Single-crystal perovskite solar cells (SC-PSCs) have emerged as a promising platform for next-generation photovoltaics owing to their long charge carrier diffusion lengths, low trap densities, and superior intrinsic stability compared to polycrystalline devices. Despite these advantages, their development has been hindered by slow performance stabilization after fabrication, difficulties in producing thin and phase-pure crystals under ambient conditions, and significant recombination losses at poorly engineered interfaces. This thesis addresses these challenges through an integrated study of performance dynamics, crystal growth pathways, and interface design, with the aim of establishing SC-PSCs as efficient and durable photovoltaic systems.

One outcome of this work is the identification of spontaneous efficiency enhancement (SEE) as a defining feature of SC-PSCs. Using different spectroscopic techniques, we demonstrate that SEE arises from the gradual release of trapped solvent molecules. Although this process can enhance device performance over time, it also introduces undesirable delays in SC-PSC performance stabilization. To resolve this, a controlled post-processing strategy is developed that accelerates efficiency gain and ensures device reproducibility.

A new interface-engineering approach is introduced in which [2-(3,6-Dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz) monolayers are assembled in situ during space-confined crystallization. This process ensures uniform surface coverage, stronger interfacial adhesion, and favorable energy-level alignment, thereby reducing recombination losses and enabling power conversion efficiencies above 24% for cesium-free SC-PSCs, coupled with enhanced operational stability.

To improve crystallization, a cosolvency-driven growth strategy is established using mixed γ-butyrolactone and 2-methoxyethanol solvents. This approach uncovers a unique solubility maximum of formamidinium lead iodide that delays nucleation, suppresses the non-perovskite δ-phase, and enables the growth of photoactive α-phase of formamidinium lead iodide thin crystals under ambient air conditions.

Building on the understanding of crystal growth, and perovskite solution chemistry, efforts were extended toward optimizing the ink formulation of wide-bandgap perovskites for polycrystalline film based tandem solar cell applications. A green solvent system comprising dimethyl sulfoxide, acetonitrile, and ethanol was developed for fabricating high-quality wide-bandgap perovskites. The incorporation of ethanol stabilized the ink by suppressing large colloid formation and extending its processing window, enabling efficient and consistent fabrication of tandem devices through a sustainable and scalable approach.

Together, these advances demonstrate that combining an understanding of performance evolution with innovative growth and interface strategies can overcome the most critical limitations of SC-PSCs. The findings narrow the performance gap with polycrystalline devices and outline clear pathways for developing efficient, stable, and scalable single-crystal perovskite photovoltaics suitable for future commercialization.