Transamidation of dimethylformamide during alkylammonium lead triiodide film formation for perovskite solar cells. Issue 1 (28th July 2016)

• Record Type: Journal Article
• Authors: Lee, Michael V.; Raga, Sonia R.; Kato, Yuichi; Leyden, Matthew R.; Ono, Luis K.; Wang, Shenghao; Qi, Yabing
• Is Part Of: Journal of materials research. Volume 32:Issue 1(2017)
• Page Start: 45
• Page End: 55
• Publication Date: 2016-07-28
• Subjects: photovoltaic, -- chemical reaction, -- secondary ion mass spectroscopy (SIMS); Materials -- Research -- Periodicals; 620.1105
• DOI: 10.1557/jmr.2016.272
• Languages: English
• ISSNs: 0884-2914

Abstract

Abstract: Abstract : Perovskite-based solar cells, typically CH3 NH3 PbI3, have reached power conversion efficiencies on par with single crystal silicon solar cells. Perovskite cells prepared with the most common perovskite solvent N, N -dimethylformamide (DMF) by different research groups exhibit disparate efficiencies and stability for nominally identical perovskite films. Although the differences can be related to processing conditions, a consistent physical cause for the differences has been lacking. Highly-sensitive time-of-flight secondary ion mass spectrometry (TOF-SIMS) reveals significant dimethylamine (DMA) included in perovskite films. TOF-SIMS and x-ray photoelectron spectroscopy results suggest DMA levels ranging from roughly 10–50%. Only the highest levels register as perovskite peak shifts in x-ray diffraction; lower levels are invisible. We propose that methylamine (MA) can react with DMF solvent by transamidation to produce dimethylamine (DMA), which then displaces some MA in perovskite crystals, seeFig. 1 . Transamidation of DMF can be catalyzed by TiO2, Al2 O3, water, or acid, but in perovskite films transamidation is inhibited by water.