Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV16)
Publication date: 28th March 2016
The physical operating mechanisms of perovskite based solar cells are subject of debate. For electrical cell characterization it is often not sufficient to study the device in steady-state [1]. To get more insight into the underlying physical processes we perform a variety of transient electrical measurements on perovskite solar cells including photo-CELIV [2], transient photocurrent (TPC), transient photovoltage (TPV), transient electroluminescence and charge extraction.
We present dynamic measurements ranging from microseconds to minutes allowing us to distinguish physical mechanisms occurring at different timescales. Using numerical drift-diffusion simulations in transient and steady-state we put existing hypotheses under test and find evidence for imbalanced charge mobilities and a time-dependent built-in voltage as attributed to ionic movement by Tress et al. [3].
By applying a forward bias for 10 minutes the ions are moved towards the electrodes enhancing the electric field within the bulk. Immediately after biasing the transient experiments are performed what enables the investigation of the influence of the ion-distribution on the charge transport.We raise the question if and how the electronic properties of the bulk change when mobile ions drift in or out and discuss whether mobile ions are a sound explanation for all effects observed in transient experiments and impedance measurements.
References:
[1] M.T. Neukom, S. Züfle, B. Ruhstaller, Organic Electronics 13, 2012.
[2] G. Juska, K. Arlauskas, M. Viliunas, J. Kocka, Phys. Rev. Lett. 84, 4946, 2000.
[3] W. Tress, N. Marinova, T. Moehl, S. M. Zakeeruddin, Mohammad Khaja Nazeeruddin and M. Grätzel, Energy Environ. Sci., 8, 995, 2015.