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Abstract title Accurate characterization of triple-junction polymer solar cells
Author MSc Di Carlo Rasi, Dario, Technische Universiteit Eindhoven, Eindhoven, The Netherlands (Presenting Author)
Co-author(s) Hendriks, Koen
Wienk, Martijn
Janssen, René
Abstract text

Triple-junction device architectures represent a promising strategy to highly efficient organic solar cells. Accurate characterization of organic triple-junction solar cells is challenging, especially with respect to determining the external quantum efficiency (EQE) of the three individual sub cells. The specific light bias conditions that are commonly used to determine the contribution of the sub cell of interest, result in an excess of charge generation in the two other sub cells. This results in the build-up of an electric field over the sub cell of interest which enhances current generation and results in an overestimation of the EQE. We have developed a protocol to correctly measure the EQE of triple-junction organic solar cells. Apart from correcting for the build-up electric field, we considered the effect of light intensity with the help of representative single-junction cells. The short-circuit current density (JSC) determined from integration of the EQE with the solar spectrum differed by up to 10% between corrected and un-corrected protocols. We validated these findings by comparing the experimentally measured EQE to the one calculated via optical-electronic modelling, obtaining an excellent agreement for a triple-junction polymer solar cell that comprises three different band gap absorber layers and with a power conversion efficiency of about 10%.