We report on the formation of wrinkle-patterned surface morphologies in cesium formamidinium-based CsₓFA₁₋ₓPb(I₁₋ᵧBrᵧ)₃ perovskite compositions with x = 0–0.3 and y = 0–0.3 under various spin-coating conditions. By varying the Cs and Br contents, the perovskite precursor solution concentration, and the spin-coating procedure, the occurrence and characteristics of the wrinkle-shaped morphology can be systematically tailored. Cs₀.₁₇FA₀.₈₃Pb(I₀.₈₃Br₀.₁₇)₃ perovskite layers were analyzed with respect to their surface roughness, microscopic structure, local and overall composition, and optoelectronic properties.
Application of these films in p–i–n perovskite solar cells (PSCs) with indium-doped tin oxide/NiOₓ/perovskite/C₆₀/bathocuproine/Cu architecture resulted in power conversion efficiencies of up to 15.3% and 17.0% for the flat and wrinkled morphologies, respectively. Interestingly, slightly red-shifted photoluminescence (PL) peaks were observed for wrinkled areas, and a direct correlation between surface topography and PL peak mapping was established. This behavior is attributed to differences in local grain size, with no indication of compositional demixing in the films.
We demonstrate that the perovskite composition, crystallization kinetics, and layer thickness strongly influence wrinkle formation, which is proposed to be related to the release of compressive strain during perovskite crystallization. This work contributes to a deeper understanding of film formation and provides pathways to further improve the efficiency of PSCs based on widely used mixed-perovskite compositions.
Autor(es):Braunger, Steffen and Mundt, Laura E. and Wolff, Christian M. and Mews, Mathias and Rehermann, Carolin and Jošt, Marko and Tejada, Alvaro and Eisenhauer, David and Becker, Christiane and Guerra, Jorge Andres and Unger, Eva and Korte, Lars and Neher, Dieter and Schubert, Martin C. and Rech, Bernd and Albrecht, Steve
Año: 2018
Título de la revista: The Journal of Physical Chemistry C
Volumen: 122
Número: 30
Url: https://doi.org/10.1021/acs.jpcc.8b06459