@article{ZhangStolterfohtArminetal.2018,
  author    = {Zhang, Shanshan and Stolterfoht, Martin and Armin, Ardalan and Lin, Qianqian and Zu, Fengshuo and Sobus, Jan and Jin, Hui and Koch, Norbert and Meredith, Paul and Burn, Paul L. and Neher, Dieter},
  title     = {Interface Engineering of Solution-Processed Hybrid Organohalide Perovskite Solar Cells},
  series = {ACS applied materials \& interfaces},
  volume    = {10},
  journal   = {ACS applied materials \& interfaces},
  number    = {25},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1944-8244},
  doi       = {10.1021/acsami.8b02503},
  pages     = {21681 -- 21687},
  year      = {2018},
  abstract  = {Engineering the interface between the perovskite absorber and the charge-transporting layers has become an important method for improving the charge extraction and open-circuit voltage (V-OC) of hybrid perovskite solar cells. Conjugated polymers are particularly suited to form the hole-transporting layer, but their hydrophobicity renders it difficult to solution-process the perovskite absorber on top. Herein, oxygen plasma treatment is introduced as a simple means to change the surface energy and work function of hydrophobic polymer interlayers for use as p-contacts in perovskite solar cells. We find that upon oxygen plasma treatment, the hydrophobic surfaces of different prototypical p-type polymers became sufficiently hydrophilic to enable subsequent perovskite junction processing. In addition, the oxygen plasma treatment also increased the ionization potential of the polymer such that it became closer to the valance band energy of the perovskite. It was also found that the oxygen plasma treatment could increase the electrical conductivity of the p-type polymers, facilitating more efficient charge extraction. On the basis of this concept, inverted MAPbI(3) perovskite devices with different oxygen plasma-treated polymers such as P3HT, P3OT, polyTPD, or PTAA were fabricated with power conversion efficiencies of up to 19\%.},
  language  = {en}
}
@article{JiangStolterfohtJinetal.2020,
  author    = {Jiang, Wei and Stolterfoht, Martin and Jin, Hui and Burn, Paul L.},
  title     = {Hole-transporting poly(dendrimer)s as electron donors for low donor organic solar cells with efficient charge transport},
  series = {Macromolecules : a publication of the American Chemical Society},
  volume    = {53},
  journal   = {Macromolecules : a publication of the American Chemical Society},
  number    = {8},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0024-9297},
  doi       = {10.1021/acs.macromol.0c00520},
  pages     = {2902 -- 2911},
  year      = {2020},
  abstract  = {Recent work on bulk-heterojunction organic solar cells has shown that photoexcitation of the electron acceptor followed by photoinduced hole transfer can play a significant role in photocurrent generation. To establish a clear understanding of the role of the donor in the photoinduced hole transfer process, we have synthesized a series of triphenylamine-based hole-transporting poly(dendrimer)s with mechanically flexible nonconjugated backbones via ring-opening metathesis polymerization and used them in low donor content solar cells. The poly(dendrimer)s were found to retain the hole transporting properties of the parent dendrimer, with hole mobilities of similar to 10(-3) cm(2)/(V s) for solution processed neat films. However, when blended with [6,6]-phenyl-C-70-butyric acid methyl ester (PC70BM), the best performing poly(dendrimer) was found to form films that had balanced and relatively high hole/electron mobilities of similar to 5 x 10(-4) cm(2) /(V s). In contrast, at the same concentration the parent dendrimer:PC70BM blend was found to have a hole mobility of 4 orders of magnitude less than the electron mobility. The balanced hole and electron mobilities for the 6 wt \% poly(dendrimer):PC70BM blend led to an absence of second-order bimolecular recombination losses at the maximum power point and resulted in a fill factor of 0.65 and a PCE 2.1\% for the devices, which was almost three times higher than the cells composed of the parent dendrimer:PC70BM blends.},
  language  = {en}
}
@article{JiangTaoStolterfohtetal.2020,
  author    = {Jiang, Wei and Tao, Chen and Stolterfoht, Martin and Jin, Hui and Stephen, Meera and Lin, Qianqian and Nagiri, Ravi C. R. and Burn, Paul L. and Gentle, Ian R.},
  title     = {Hole-transporting materials for low donor content organic solar cells},
  series = {Organic electronics : physics, materials and applications},
  volume    = {76},
  journal   = {Organic electronics : physics, materials and applications},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1566-1199},
  doi       = {10.1016/j.orgel.2019.105480},
  pages     = {7},
  year      = {2020},
  abstract  = {Low donor content solar cells are an intriguing class of photovoltaic device about which there is still considerable discussion with respect to their mode of operation. We have synthesized a series of triphenylamine-based materials for use in low donor content devices with the electron accepting [6,6]-phenyl-C71-butyric acid methyl ester (PC(7)0BM). The triphenylamine-based materials absorb light in the near UV enabling the PC(7)0BM to be be the main light absorbing organic semiconducting material in the solar cell. It was found that the devices did not operate as classical Schottky junctions but rather photocurrent was generated by hole transfer from the photo-excited PC(7)0BM to the triphenylamine-based donors. We found that replacing the methoxy surface groups with methyl groups on the donor material led to a decrease in hole mobility for the neat films, which was due to the methyl substituted materials having the propensity to aggregate. The thermodynamic drive to aggregate was advantageous for the performance of the low donor content (6 wt\%) films. It was found that the 6 wt\% donor devices generally gave higher performance than devices containing 50 wt\% of the donor.},
  language  = {en}
}