@article{LaiLuoZwirneretal.2022,
  author    = {Lai, Huagui and Luo, Jincheng and Zwirner, Yannick and Olthof, Selina and Wieczorek, Alexander and Ye, Fangyuan and Jeangros, Quentin and Yin, Xinxing and Akhundova, Fatima and Ma, Tianshu and He, Rui and Kothandaraman, Radha K. and Chin, Xinyu and Gilshtein, Evgeniia and Muller, Andre and Wang, Changlei and Thiesbrummel, Jarla and Siol, Sebastian and Prieto, Jose Marquez and Unold, Thomas and Stolterfoht, Martin and Chen, Cong and Tiwari, Ayodhya N. and Zhao, Dewei and Fu, Fan},
  title     = {High-performance flexible all-Perovskite tandem solar cells with reduced V-OC-deficit in wide-bandgap subcell},
  series = {Advanced energy materials},
  volume    = {12},
  journal   = {Advanced energy materials},
  number    = {45},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1614-6832},
  doi       = {10.1002/aenm.202202438},
  pages     = {12},
  year      = {2022},
  abstract  = {Among various types of perovskite-based tandem solar cells (TSCs), all-perovskite TSCs are of particular attractiveness for building- and vehicle-integrated photovoltaics, or space energy areas as they can be fabricated on flexible and lightweight substrates with a very high power-to-weight ratio. However, the efficiency of flexible all-perovskite tandems is lagging far behind their rigid counterparts primarily due to the challenges in developing efficient wide-bandgap (WBG) perovskite solar cells on the flexible substrates as well as their low open-circuit voltage (V-OC). Here, it is reported that the use of self-assembled monolayers as hole-selective contact effectively suppresses the interfacial recombination and allows the subsequent uniform growth of a 1.77 eV WBG perovskite with superior optoelectronic quality. In addition, a postdeposition treatment with 2-thiopheneethylammonium chloride is employed to further suppress the bulk and interfacial recombination, boosting the V-OC of the WBG top cell to 1.29 V. Based on this, the first proof-of-concept four-terminal all-perovskite flexible TSC with a power conversion efficiency of 22.6\% is presented. When integrating into two-terminal flexible tandems, 23.8\% flexible all-perovskite TSCs with a superior V-OC of 2.1 V is achieved, which is on par with the V-OC reported on the 28\% all-perovskite tandems grown on the rigid substrate.},
  language  = {en}
}
@article{CaprioglioZuWolffetal.2019,
  author    = {Caprioglio, Pietro and Zu, Fengshuo and Wolff, Christian Michael and Prieto, Jose A. Marquez and Stolterfoht, Martin and Becker, Pascal and Koch, Norbert and Unold, Thomas and Rech, Bernd and Albrecht, Steve and Neher, Dieter},
  title     = {High open circuit voltages in pin-type perovskite solar cells through strontium addition},
  series = {Sustainable Energy \& Fuels},
  volume    = {3},
  journal   = {Sustainable Energy \& Fuels},
  number    = {2},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2398-4902},
  doi       = {10.1039/c8se00509e},
  pages     = {550 -- 563},
  year      = {2019},
  abstract  = {The incorporation of even small amounts of strontium (Sr) into lead-base hybrid quadruple cation perovskite solar cells results in a systematic increase of the open circuit voltage (V-oc) in pin-type perovskite solar cells. We demonstrate via absolute and transient photoluminescence (PL) experiments how the incorporation of Sr significantly reduces the non-radiative recombination losses in the neat perovskite layer. We show that Sr segregates at the perovskite surface, where it induces important changes of morphology and energetics. Notably, the Sr-enriched surface exhibits a wider band gap and a more n-type character, accompanied with significantly stronger surface band bending. As a result, we observe a significant increase of the quasi-Fermi level splitting in the neat perovskite by reduced surface recombination and more importantly, a strong reduction of losses attributed to non-radiative recombination at the interface to the C-60 electron-transporting layer. The resulting solar cells exhibited a V-oc of 1.18 V, which could be further improved to nearly 1.23 V through addition of a thin polymer interlayer, reducing the non-radiative voltage loss to only 110 meV. Our work shows that simply adding a small amount of Sr to the precursor solutions induces a beneficial surface modification in the perovskite, without requiring any post treatment, resulting in high efficiency solar cells with power conversion efficiency (PCE) up to 20.3\%. Our results demonstrate very high V-oc values and efficiencies in Sr-containing quadruple cation perovskite pin-type solar cells and highlight the imperative importance of addressing and minimizing the recombination losses at the interface between perovskite and charge transporting layer.},
  language  = {en}
}