Photocurrent Spectroscopy of Perovskite Layers and Solar Cells: A Sensitive Probe of Material Degradation

Jakub Holovský, Stefaan De Wolf, Jérémie Werner, Zdeněk Remeš, Martin Müller, Neda Neykova, Martin Ledinský, Ladislava Černá, Pavel Hrzina, Philipp Löper, Bjoern Niesen, Christophe Ballif

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Optical absorptance spectroscopy of polycrystalline CHNHPbI films usually indicates the presence of a PbI phase, either as a preparation residue or due to film degradation, but gives no insight on how this may affect electrical properties. Here, we apply photocurrent spectroscopy to both perovskite solar cells and coplanar-contacted layers at various stages of degradation. In both cases, we find that the presence of a PbI phase restricts charge-carrier transport, suggesting that PbI encapsulates CHNHPbI grains. We also find that PbI injects holes into the CHNHPbI grains, increasing the apparent photosensitivity of PbI. This phenomenon, known as modulation doping, is absent in the photocurrent spectra of solar cells, where holes and electrons have to be collected in pairs. This interpretation provides insights into the photogeneration and carrier transport in dual-phase perovskites.
Original languageEnglish (US)
Pages (from-to)838-843
Number of pages6
JournalThe Journal of Physical Chemistry Letters
Volume8
Issue number4
DOIs
StatePublished - Feb 6 2017

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