A Closer Look into Two-Step Perovskite Conversion with X-ray Scattering.
Recently, hybrid perovskites have gathered much interest as alternative materials for the fabrication of highly efficient and cost-competitive solar cells; however, many questions regarding perovskite crystal formation and deposition methods remain. Here we have applied a two-step protocol where a crystalline PbI2 precursor film is converted to MAPbI3-xClx perovskite upon immersion in a mixed solution of methylammonium iodide and methylammonium chloride. We have investigated both films with grazing incidence small-angle X-ray scattering to probe the inner film morphology. Our results demonstrate a strong link between lateral crystal sizes in the films before and after conversion, which we attribute to laterally confined crystal growth. Additionally, we observe an accumulation of smaller grains within the bulk in contrast with the surface. Thus, our results help to elucidate the crystallization process of perovskite films deposited via a two-step technique that is crucial for controlled film formation, improved reproducibility, and high photovoltaic performance.
†Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany.
Johannes
J
Schlipf
‡Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), Butenandtstr. 5-13, 81377 München, Germany.
Pablo
P
Docampo
†Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany.
Christoph J
CJ
Schaffer
†Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany.
Volker
V
Körstgens
†Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany.
Lorenz
L
Bießmann
‡Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), Butenandtstr. 5-13, 81377 München, Germany.
Fabian
F
Hanusch
‡Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), Butenandtstr. 5-13, 81377 München, Germany.
Nadja
N
Giesbrecht
§Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, 34149 Trieste, Italy.
Sigrid
S
Bernstorff
‡Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), Butenandtstr. 5-13, 81377 München, Germany.
Thomas
T
Bein
†Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany.
Peter
P
Müller-Buschbaum
GISAXS; Ostwald ripening; confined growth; conversion; crystal size; perovskite solar cell