Stark Effect in Perovskite/TiO2 Solar Cells: Evidence of Local Interfacial Order

• Published in: Nano letters Vol. 14; no. 4; pp. 2168 - 2174
• Main Authors: Roiati, Vittoria, Mosconi, Edoardo, Listorti, Andrea, Colella, Silvia, Gigli, Giuseppe, De Angelis, Filippo
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09.04.2014
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states; Energy; Exact sciences and technology; Level splitting and interactions; Methods of electronic structure calculations; Natural energy; Photovoltaic conversion; Physics; Solar cells. Photoelectrochemical cells; Solar energy; Spin-orbit coupling, zeeman, stark, and strain splitting, jahn-teller effect; hybrid solar cells; Stark spectroscopy; Perovskites; DFT investigations; Solar cells; Thin films; Interfaces; Porous materials; Theoretical study; Density functional method; Stark effect; Photovoltaic conversion; Mesoporosity
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl500544c

To unveil the mechanisms controlling photovoltaic conversion in high-performing perovskite-based mesostructured solar cells, we focus on the key role played by the mesoporous oxide/perovskite interface. We employ several spectroscopic techniques to design a complete scenario and corroborate our results with first principle density functional theory calculations. In particular Stark spectroscopy, a powerful tool allowing interface-sensitive analysis is employed to prove the existence of oriented permanent dipoles, consistent with the hypothesis of an ordered perovskite layer, close to the oxide surface. The existence of a structural order, promoted by specific local interactions, could be one of the decisive reasons for highly efficient carriers transport within perovskite films.