@article{PranavBenduhnNymanetal.2021,
  author    = {Pranav, Manasi and Benduhn, Johannes and Nyman, Mathias and Hosseini, Seyed Mehrdad and Kublitski, Jonas and Shoaee, Safa and Neher, Dieter and Leo, Karl and Spoltore, Donato},
  title     = {Enhanced charge selectivity via anodic-C60 layer reduces nonradiative losses in organic solar cells},
  series = {ACS applied materials \& interfaces},
  volume    = {13},
  journal   = {ACS applied materials \& interfaces},
  number    = {10},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1944-8244},
  doi       = {10.1021/acsami.1c00049},
  pages     = {12603 -- 12609},
  year      = {2021},
  abstract  = {Interfacial layers in conjunction with suitable charge-transport layers can significantly improve the performance of optoelectronic devices by facilitating efficient charge carrier injection and extraction. This work uses a neat C-60 interlayer on the anode to experimentally reveal that surface recombination is a significant contributor to nonradiative recombination losses in organic solar cells. These losses are shown to proportionally increase with the extent of contact between donor molecules in the photoactive layer and a molybdenum oxide (MoO3) hole extraction layer, proven by calculating voltage losses in low- and high-donor-content bulk heterojunction device architectures. Using a novel in-device determination of the built-in voltage, the suppression of surface recombination, due to the insertion of a thin anodic-C-60 interlayer on MoO3, is attributed to an enhanced built-in potential. The increased built-in voltage reduces the presence of minority charge carriers at the electrodes-a new perspective on the principle of selective charge extraction layers. The benefit to device efficiency is limited by a critical interlayer thickness, which depends on the donor material in bilayer devices. Given the high popularity of MoO3 as an efficient hole extraction and injection layer and the increasingly popular discussion on interfacial phenomena in organic optoelectronic devices, these findings are relevant to and address different branches of organic electronics, providing insights for future device design.},
  language  = {en}
}
@article{PranavHultzschMusiienkoetal.2023,
  author    = {Pranav, Manasi and Hultzsch, Thomas and Musiienko, Artem and Sun, Bowen and Shukla, Atul and Jaiser, Frank and Shoaee, Safa and Neher, Dieter},
  title     = {Anticorrelated photoluminescence and free charge generation proves field-assisted exciton dissociation in low-offset PM6:Y5 organic solar cells},
  series = {APL materials : high impact open access journal in functional materials science},
  volume    = {11},
  journal   = {APL materials : high impact open access journal in functional materials science},
  number    = {6},
  publisher = {AIP Publishing},
  address   = {Melville},
  issn      = {2166-532X},
  doi       = {10.1063/5.0151580},
  pages     = {8},
  year      = {2023},
  abstract  = {Understanding the origin of inefficient photocurrent generation in organic solar cells with low energy offset remains key to realizing high-performance donor-acceptor systems. Here, we probe the origin of field-dependent free-charge generation and photoluminescence in wnon-fullereneacceptor (NFA)-based organic solar cells using the polymer PM6 and the NFA Y5-a non-halogenated sibling to Y6, with a smaller energetic offset to PM6. By performing time-delayed collection field (TDCF) measurements on a variety of samples with different electron transport layers and active layer thickness, we show that the fill factor and photocurrent are limited by field-dependent free charge generation in the bulk of the blend. We also introduce a new method of TDCF called m-TDCF to prove the absence of artifacts from non-geminate recombination of photogenerated and dark charge carriers near the electrodes. We then correlate free charge generation with steady-state photoluminescence intensity and find perfect anticorrelation between these two properties. Through this, we conclude that photocurrent generation in this low-offset system is entirely controlled by the field-dependent dissociation of local excitons into charge-transfer states. (c) 2023 Author(s).},
  language  = {en}
}