Inverted hysteresis and negative capacitance as a moisture effect in Perovskite Solar Cell.
Agustin O. Alvarez a, Ramón Arcas a, Loengrid Bethencourt b, Agustin Bou a, Elena Mas-Marzá a, Francisco Fabregat-Santiago a
a Institute of Advanced Materials (INAM), University Jaume I, Avenida de Vicent Sos Baynat, s/n, 12006 Castelló de la Plana, Castellón (Spain)
b Grupo de Desarrollo de Materiales y Estudios Ambientales, Universidad de la República, Rocha 27000, Uruguay
Pending, Agustin O. Alvarez, presentation 111
Publication date: 25th November 2019

Organic-inorganic hybrid perovskites are currently the most promising materials for the next-generation solar cells (PSCs). This feature is mainly due to their excellent photovoltaic performances, such as high absorption coefficient, high charge carrier mobility, and long diffusion length. One of the main factors determining long term stability of the PSCs is the access of moisture to perovskite, therefore it is crucial to insulate the material from the environment and to develop tools that indicate when humidity is penetrating the PSCs device. So far, several effects that moisture produces on the PSCs, such as the formation of perovskite mono- and di-hydrates species or the associated conductivity increase of the perovskite film have been shown. Here we show how moisture drives cyclic voltammetry behaviour of PSCs from normal to inverted hysteresis when we increase environmental relative humidity from 0% to 60%. This behaviour ended in the decomposition of the perovskite and failure of the device. When analysing the PSCs with impedance spectroscopy, we were able to observe a transition from a capacitive behaviour, dominated by a giant capacitive, to a spectrum dominated by a negative capacitance (or inductance). The first case is found in well-behaving samples while the second case is related to samples that degraded irreversibly. We can use this characteristic behaviour that we observed for several samples to estimate and control the degradation process in PSCs.

Results that that have resulted in this poster has received funding from the ITN-MAESTRO project from European Union’s Horizon 2020 research and innovation programme under grant agreement No 764787.

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