Quantifying loss-mechanisms related to charge carrier collection in thin-film solar cells (Conference Presentation)

Abstract

Processes taking place at contacts are of particular importance in organic and perovskite solar cells where selective contacts that are able to efficiently collect majority carriers, simultaneously blocking minority carriers are desired. The surface recombination velocity S_R, describing the quality of the contact interface, is a key parameter in obtaining an increased understanding of the kinetics taking place at contacts in thin-film devices [1]. We have extended the analytical framework of the charge extraction by linearly increasing voltage (CELIV) theory taking the effect of built-in voltage, diffusion and band-bending into account [2] and show how we can experimentally quantify loss mechanisms in charge collection [3-4]. We have derived analytical expressions describing the effective reduction of the built-in voltage and the (effective) open-circuit voltage providing means to quantify and distinguish various (loss) mechanisms for contact related effects in thin film solar cells [2-4]. References [1] O. Sandberg, M. Nyman, R. Osterbacka, Physical Review Applied 1, 024003 (2014) [2] O. Sandberg, M. Nyman, R. Osterbacka, Organic Electronics 15, 3413-3420 (2015) [3] A. Sundqvist, M. Nyman, O. Sandberg, S. Sanden, J.-H. Smatt, and R. Osterbacka, Advanced Energy Materials, 1502265 (2016) [4] O.J. Sandberg, et. al, Physical Review Letters, 118, 076601 (2017).