@article{PerdigonToroLeQuangPhuongElleretal.2022,
  author    = {Perdigon-Toro, Lorena and Le Quang Phuong, and Eller, Fabian and Freychet, Guillaume and Saglamkaya, Elifnaz and Khan, Jafar and Wei, Qingya and Zeiske, Stefan and Kroh, Daniel and Wedler, Stefan and Koehler, Anna and Armin, Ardalan and Laquai, Frederic and Herzig, Eva M. and Zou, Yingping and Shoaee, Safa and Neher, Dieter},
  title     = {Understanding the role of order in Y-series non-fullerene solar cells to realize high open-circuit voltages},
  series = {Advanced energy materials},
  volume    = {12},
  journal   = {Advanced energy materials},
  number    = {12},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1614-6832},
  doi       = {10.1002/aenm.202103422},
  pages     = {13},
  year      = {2022},
  abstract  = {Non-fullerene acceptors (NFAs) as used in state-of-the-art organic solar cells feature highly crystalline layers that go along with low energetic disorder. Here, the crucial role of energetic disorder in blends of the donor polymer PM6 with two Y-series NFAs, Y6, and N4 is studied. By performing temperature-dependent charge transport and recombination studies, a consistent picture of the shape of the density of state distributions for free charges in the two blends is developed, allowing an analytical description of the dependence of the open-circuit voltage V-OC on temperature and illumination intensity. Disorder is found to influence the value of the V-OC at room temperature, but also its progression with temperature. Here, the PM6:Y6 blend benefits substantially from its narrower state distributions. The analysis also shows that the energy of the equilibrated free charge population is well below the energy of the NFA singlet excitons for both blends and possibly below the energy of the populated charge transfer manifold, indicating a down-hill driving force for free charge formation. It is concluded that energetic disorder of charge-separated states has to be considered in the analysis of the photovoltaic properties, even for the more ordered PM6:Y6 blend.},
  language  = {en}
}
@article{WolffZuPaulkeetal.2017,
  author    = {Wolff, Christian Michael and Zu, Fengshuo and Paulke, Andreas and Perdigon-Toro, Lorena and Koch, Norbert and Neher, Dieter},
  title     = {Reduced Interface-Mediated Recombination for High Open-Circuit Voltages in CH3NH3PbI3 Solar Cells},
  series = {Advanced materials},
  volume    = {29},
  journal   = {Advanced materials},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0935-9648},
  doi       = {10.1002/adma.201700159},
  pages     = {8},
  year      = {2017},
  abstract  = {Perovskite solar cells with all-organic transport layers exhibit efficiencies rivaling their counterparts that employ inorganic transport layers, while avoiding high-temperature processing. Herein, it is investigated how the choice of the fullerene derivative employed in the electron-transporting layer of inverted perovskite cells affects the open-circuit voltage (V-OC). It is shown that nonradiative recombination mediated by the electron-transporting layer is the limiting factor for the V-OC in the cells. By inserting an ultrathin layer of an insulating polymer between the active CH3NH3PbI3 perovskite and the fullerene, an external radiative efficiency of up to 0.3\%, a V-OC as high as 1.16 V, and a power conversion efficiency of 19.4\% are realized. The results show that the reduction of nonradiative recombination due to charge-blocking at the perovskite/organic interface is more important than proper level alignment in the search for ideal selective contacts toward high V-OC and efficiency.},
  language  = {en}
}
@article{NikolisBenduhnHolzmuelleretal.2017,
  author    = {Nikolis, Vasileios C. and Benduhn, Johannes and Holzmueller, Felix and Piersimoni, Fortunato and Lau, Matthias and Zeika, Olaf and Neher, Dieter and Koerner, Christian and Spoltore, Donato and Vandewal, Koen},
  title     = {Reducing Voltage Losses in Cascade Organic Solar Cells while Maintaining High External Quantum Efficiencies},
  series = {dvanced energy materials},
  volume    = {7},
  journal   = {dvanced energy materials},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1614-6832},
  doi       = {10.1002/aenm.201700855},
  pages     = {122 -- 136},
  year      = {2017},
  abstract  = {High photon energy losses limit the open-circuit voltage (V-OC) and power conversion efficiency of organic solar cells (OSCs). In this work, an optimization route is presented which increases the V-OC by reducing the interfacial area between donor (D) and acceptor (A). This optimization route concerns a cascade device architecture in which the introduction of discontinuous interlayers between alpha-sexithiophene (alpha-6T) (D) and chloroboron subnaphthalocyanine (SubNc) (A) increases the V-OC of an alpha-6T/SubNc/SubPc fullerene-free cascade OSC from 0.98 V to 1.16 V. This increase of 0.18 V is attributed solely to the suppression of nonradiative recombination at the D-A interface. By accurately measuring the optical gap (E-opt) and the energy of the charge-transfer state (E-CT) of the studied OSC, a detailed analysis of the overall voltage losses is performed. E-opt - qV(OC) losses of 0.58 eV, which are among the lowest observed for OSCs, are obtained. Most importantly, for the V-OC-optimized devices, the low-energy (700 nm) external quantum efficiency (EQE) peak remains high at 79\%, despite a minimal driving force for charge separation of less than 10 meV. This work shows that low-voltage losses can be combined with a high EQE in organic photovoltaic devices.},
  language  = {en}
}