Origin of Ionic Inhomogeneity in MAPb(IxBr1-x)3 Perovskite Thin Films Revealed by In-Situ Spectroscopy during Spin Coating and Annealing

被引：20

作者：

Rehermann, Carolin ^{[1
]}

Merdasa, Aboma ^{[1
,4
]}

Suchan, Klara ^{[2
,3
]}

Schroeder, Vincent ^{[5
]}

Mathies, Florian ^{[1
]}

Unger, Eva L. ^{[1
,2
,3
]}

机构：

[1] Helmholtz Zentrum Berlin Mat & Energie GmbH, HySPRINT Innovat Lab, Young Investigator Grp Hybrid Mat Format & Scalin, D-12489 Berlin, Germany

[2] Lund Univ, Chem Phys, S-22100 Lund, Sweden

[3] Lund Univ, NanoLund, S-22100 Lund, Sweden

[4] Lund Univ, Dept Phys, S-22362 Lund, Sweden

[5] Humboldt Univ, Inst Phys, Inst Chem, IRIS Adlershof, D-12489 Berlin, Germany

来源：

ACS APPLIED MATERIALS & INTERFACES | 2020年 / 12卷 / 27期

基金：

瑞典研究理事会;

关键词：

perovskites; mixed halides; formation process; homogeneity; in-situ spectroscopy; LEAD HALIDE PEROVSKITES; PHASE SEGREGATION; BR; STABILITY; BROMIDE; IODIDE; DONOR;

D O I：

10.1021/acsami.0c05894

中图分类号：

TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

Irradiation-induced phase segregation in mixed methylammonium halide perovskite samples such as methylammonium lead bromide-iodide, MAPb(IxBr1-x)(3), is being studied intensively because it limits the efficiency of wide band gap perovskite solar cells. It has been postulated that this phenomenon depends on the intrinsic ionic (in)homogeneity in samples already induced during film formation. A deeper understanding of the MAPb(IxBr1-x)(3) formation processes and the influence of the halide ratio, solvents, and the perovskite precursor composition as well as the influence of processing parameters during deposition, e.g., spin coating and annealing parameters, is still lacking. Here, we use a fiber optic-based optical in-situ setup to study the formation processes of the MAPb(IxBr1-x)(3) series on a subsecond time scale during spin coating and thermal annealing. In-situ UV-vis measurements during spin coating reveal the influence of different halide ratios, x, in the precursor solution on the preferential crystallization of the phase. Pure bromide samples directly form a perovskite phase, samples with high iodide content form a solvate intermediate phase, and samples with a mixed stoichiometry between 0.1 <= x <= 0.6 form both. This leads to a heterogeneous formation process via two competing reaction pathways, that leads to a heterogeneous mixture of phases, during spin coating and rationalizes the compositional heterogeneity of mixed bromide-iodide samples even after annealing.

引用

页码：30343 / 30352

页数：10