Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 90: Poster III
HL 90.32: Poster
Donnerstag, 10. März 2016, 16:00–19:00, Poster A
Multilayer fullerene-free organic solar cells with low energy losses — •Vasileios Christos Nikolis, Donato Spoltore, Johannes Benduhn, Felix Holzmüller, Christian Körner, and Koen Vandewal — Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Str. 1, 01069 Dresden, Germany
The generation of free charge carriers at interfaces between organic electron donors (D) and electron acceptors (A) can be very efficient, enabling organic solar cells with external quantum efficiencies (EQE) higher than 80 % and internal quantum efficiencies (IQE) approaching 100 %. On the other hand, recombination of free charge carriers at the D-A interface reduces the open-circuit voltage, and overall power conversion efficiency (PCE) of photovoltaic devices comprising such interfaces.
In this study, we introduce an optimization route in order to improve the Voc in multilayer organic solar cells. The deposition of an ultrathin interlayer between D and A creates a discontinuous layer which reduces the D-A interface area and thus free carrier recombination, while keeping a high free carrier generation yield. Investigating a series of interlayers and multilayer device architectures, we achieve PCE’s > 7.5 %. Most notably, this strategy enables a Voc of 1.18 V with a peak external quantum efficiency of 78 % at 1.77 eV (700 nm). Such high quantum efficiencies combined with the very low voltage losses below 0.59 V are unprecedented for organic solar cells. Furthermore, this work provides clear pathways for the minimization of photon energy losses by manipulation of the organic photovoltaic device architecture.