Investigation of CH3NH3PbI3 Degradation Rates and Mechanisms in Controlled Humidity Environments Using in Situ Techniques

• Published in: ACS nano Vol. 9; no. 2; pp. 1955 - 1963
• Main Authors: Yang, Jinli, Siempelkamp, Braden D, Liu, Dianyi, Kelly, Timothy L
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 24.02.2015
• Subjects: perovskites; decomposition; GIXRD; moisture; relative humidity
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn506864k

Perovskite solar cells have rapidly advanced to the forefront of solution-processable photovoltaic devices, but the CH3NH3PbI3 semiconductor decomposes rapidly in moist air, limiting their commercial utility. In this work, we report a quantitative and systematic investigation of perovskite degradation processes. By carefully controlling the relative humidity of an environmental chamber and using in situ absorption spectroscopy and in situ grazing incidence X-ray diffraction to monitor phase changes in perovskite degradation process, we demonstrate the formation of a hydrated intermediate containing isolated PbI6 4– octahedra as the first step of the degradation mechanism. We also show that the identity of the hole transport layer can have a dramatic impact on the stability of the underlying perovskite film, suggesting a route toward perovskite solar cells with long device lifetimes and a resistance to humidity.