@article{LiBenduhnQiaoetal.2019,
  author    = {Li, Tian-yi and Benduhn, Johannes and Qiao, Zhi and Liu, Yuan and Li, Yue and Shivhare, Rishi and Jaiser, Frank and Wang, Pei and Ma, Jie and Zeika, Olaf and Neher, Dieter and Mannsfeld, Stefan C. B. and Ma, Zaifei and Vandewal, Koen and Leo, Karl},
  title     = {Effect of H- and J-Aggregation on the Photophysical and Voltage Loss of Boron Dipyrromethene Small Molecules in Vacuum-Deposited Organic Solar Cells},
  series = {The journal of physical chemistry letters},
  volume    = {10},
  journal   = {The journal of physical chemistry letters},
  number    = {11},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1948-7185},
  doi       = {10.1021/acs.jpclett.9b01222},
  pages     = {2684 -- 2691},
  year      = {2019},
  abstract  = {An understanding of the factors limiting the open-circuit voltage (V-oc) and related photon energy loss mechanisms is critical to increase the power conversion efficiency (PCE) of small-molecule organic solar cells (OSCs), especially those with near-infrared (NIR) absorbers. In this work, two NIR boron dipyrromethene (BODIPY) molecules are characterized for application in planar (PHJ) and bulk (BHJ) heterojunction OSCs. When two H atoms are substituted by F atoms on the peripheral phenyl rings of the molecules, the molecular aggregation type in the thin film changes from the H-type to J-type. For PHJ devices, the nonradiative voltage loss of 0.35 V in the J-aggregated BODIPY is lower than that of 0.49 V in the H-aggregated device. In BHJ devices with a nonradiative voltage loss of 0.35 V, a PCE of 5.5\% is achieved with an external quantum efficiency (EQE) maximum of 68\% at 700 nm.},
  language  = {en}
}
@article{LiBenduhnLietal.2018,
  author    = {Li, Tian-yi and Benduhn, Johannes and Li, Yue and Jaiser, Frank and Spoltore, Donato and Zeika, Olaf and Ma, Zaifei and Neher, Dieter and Vandewal, Koen and Leo, Karl},
  title     = {Boron dipyrromethene (BODIPY) with meso-perfluorinated alkyl substituents as near infrared donors in organic solar cells},
  series = {Journal of materials chemistry : A, Materials for energy and sustainability},
  volume    = {6},
  journal   = {Journal of materials chemistry : A, Materials for energy and sustainability},
  number    = {38},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2050-7488},
  doi       = {10.1039/c8ta06261g},
  pages     = {18583 -- 18591},
  year      = {2018},
  abstract  = {Three furan-fused BODIPYs were synthesized with perfluorinated methyl, ethyl and n-propyl groups on the meso-carbon. They were obtained with high yields by reacting the furan-fused 2-carboxylpyrrole in corresponding perfluorinated acid and anhydride. With the increase in perfluorinated alkyl chain length, the molecular packing in the single crystal is influenced, showing increasing stacking distance and decreasing slope angle. All the BODIPYs were characterized as intense absorbers in near infrared region in solid state, peaking at similar to 800 nm with absorption coefficient of over 280 000 cm(-1). Facilitated by high thermal stability, the furan-fused BODIPYs were employed in vacuum-deposited organic solar cells as electron donors. All devices exhibit PCE over 6.0\% with the EQE maximum reaching 70\% at similar to 790 nm. The chemical modification of the BODIPY donors have certain influence on the active layer morphology, and the highest PCE of 6.4\% was obtained with a notably high jsc of 13.6 mA cm(-2). Sensitive EQE and electroluminance studies indicated that the energy losses generated by the formation of a charge transfer state and the radiative recombination at the donor-acceptor interface were comparable in the range of 0.14-0.19 V, while non-radiative recombination energy loss of 0.38 V was the main energy loss route resulting in the moderate V-oc of 0.76 V.},
  language  = {en}
}
@article{YangGhoshRoeseretal.2022,
  author    = {Yang, Jin and Ghosh, Samrat and Roeser, J{\´e}r{\^o}me and Acharjya, Amitava and Penschke, Christopher and Tsutsui, Yusuke and Rabeah, Jabor and Wang, Tianyi and Tameu, Simon Yves Djoko and Ye, Meng-Yang and Gr{\"u}neberg, Julia and Li, Shuang and Li, Changxia and Schomaecker, Reinhard and Van de Krol, Roel and Seki, Shu and Saalfrank, Peter and Thomas, Arne},
  title     = {Constitutional isomerism of the linkages in donor-acceptor covalent organic frameworks and its impact on photocatalysis},
  series = {Nature Communications},
  volume    = {13},
  journal   = {Nature Communications},
  number    = {1},
  publisher = {Nature Publishing Group UK},
  address   = {[London]},
  issn      = {2041-1723},
  doi       = {10.1038/s41467-022-33875-9},
  pages     = {10},
  year      = {2022},
  abstract  = {When new covalent organic frameworks (COFs) are designed, the main efforts are typically focused on selecting specific building blocks with certain geometries and properties to control the structure and function of the final COFs. The nature of the linkage (imine, boroxine, vinyl, etc.) between these building blocks naturally also defines their properties. However, besides the linkage type, the orientation, i.e., the constitutional isomerism of these linkages, has rarely been considered so far as an essential aspect. In this work, three pairs of constitutionally isomeric imine-linked donor-acceptor (D-A) COFs are synthesized, which are different in the orientation of the imine bonds (D-C=N-A (DCNA) and D-N=C-A (DNCA)). The constitutional isomers show substantial differences in their photophysical properties and consequently in their photocatalytic performance. Indeed, all DCNA COFs show enhanced photocatalytic H2 evolution performance than the corresponding DNCA COFs. Besides the imine COFs shown here, it can be concluded that the proposed concept of constitutional isomerism of linkages in COFs is quite universal and should be considered when designing and tuning the properties of COFs.},
  language  = {en}
}