Determination of Surface Recombination Velocity at the TiO2 Contact
Syeda Qudsia a, Staffan Dahlström b, Christian Ahläng b, Mathias Nyman b, Ronald Österbacka b, Jan-Henrik Smått a
a Laboratory of Molecular Science and Engineering, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland, Finland
b Physics, Faculty of Science and Engineering, Åbo Akademi University, Turku Finland, Finland
International Conference on Hybrid and Organic Photovoltaics
Proceedings of Online International Conference on Hybrid and Organic Photovoltaics (OnlineHOPV20)
Online, Spain, 2020 May 26th - 29th
Organizers: Tracey Clarke, James Durrant, Annamaria Petrozza and Trystan Watson
Poster, Syeda Qudsia, 107
Publication date: 22nd May 2020
ePoster: 

Titania, TiO2, is a commonly applied electron transport layer in thin-film solar cells, e.g. in perovskite and in organic solar cells. Energy levels of TiO2 align well with most of the light-absorbing materials used in thin-film solar cells and compact layers of titania are assumed to selectively collect electrons while blocking the extraction of holes, thereby reducing surface recombination.

In this study, we have used the charge extraction by linearly increasing voltage (CELIV) technique to clarify the hole-blocking properties of TiO2 compact layers by determining the surface recombination velocity for holes at the TiO2 interface [1]. Different thicknesses of titania layers were prepared by the dip-coating method. The effect of UV-light exposure of TiO2 was also characterized by performing CELIV on the same layers before and after UV soaking.

Our results show that changing the thickness of titania layers results in a slight decrease in the surface recombination velocities with increasing thickness. On the other hand, UV-light soaking diminishes the hole-blocking properties of TiO2 to a great extent, thereby surface recombination velocities could not be calculated after UV light exposure.

Financial support from Academy of Finland (grant number 308307) and the Jane and Aatos Erkko Foundation (ASPIRE project) is acknowledged.

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