Multidimensional photoresponsive molecular architectures for high performance solar cells
Final Report Abstract
Within this project innovative means to increase the overall performance and efficiency of organic solar cells (OSCs) were developed. On the one hand, different light-harvesting structures as well as possibilities for material optimization and nanoparticle doping were investigated. On the other hand, multiscale simulations of bulk heterojunction solar cells were performed to improve the understanding of the physical processes and thus help to optimize OSCs. Regarding light harvesting, a tailored lithographic system was developed to successfully fabricate complex surface structures based on biomimetic approaches. The most promising structure revealed to be a deterministic aperiodic golden-angle Vogel spiral having a symmetry of the golden cut as it can be found in sunflowers or plant leave morphologies. Its application on organic solar cells architectures resulted in a significant increase in power conversion efficiency of 18%. Moreover different circular-symmetric two-dimensional arrangements of the aperiodic Rudin-Shapiro and Thue-Morse sequences were modelled. The enhancement of absorption in OSCs when using correspondingly fabricated phase gratings was calculated, and the most promising structure was further optimized in terms of its lateral feature size and depth to find an optimal deterministic aperiodic surface structure. Furthermore, the motion of azopolymer molecules under different illumination configurations was modelled, considering the influence of polarization as well as the finite size of the aperiodic structures. Thereby, the effect of surface relief gratings on the overall solar cell performance under these conditions could be explained. To improve the efficiency of organic solar cells by material optimization, a novel and promising organic solar cell type based on the non-fullerene acceptor ITIC and the polymer donor PBDB-T was fabricated. To investigate its suitability for real-life applications, the stability of the cell’s power conversion efficiency under illumination, heat, air and combinations thereof was characterized. In addition, theoretical studies of other novel acceptor molecules (TPH, TPH-SE, NITI, ZITI and ATT-2) were performed. These dealt with possibilities for further molecular optimizations and investigation of the structural causes for characteristic optical properties of these molecules. Various upconversion nanoparticles based on the host material NaYF4 doped with different lanthanide ions were investigated for their suitability for integration into OSCs and enhancement of power conversion efficiency. Successful integration without efficiency loss was achieved for β-NaYF4:Yb3+,Er3+ nanoparticles. However, the upconversion was weak and could not be detected after integration into the OSCs, which may be due to the aggregation of the nanoparticles. Finally, various multiscale simulations of bulk heterojunction solar cells were performed. More specifically, multiscale simulations of PPDI:PBDT-TS1 bulk heterojunctions were conducted to determine their morphology at different temperatures. In addition, different models for charge transport in DiPBI:P3HT and PPDI:PBDT-TS1 systems were compared and their disparities presented. For πstacked P3HT molecules ab initio simulations of exciton diffusion in dependence of intermolecular distance were performed using a newly developed method. Overall, the results obtained in this project can contribute to improving the performance of organic solar cells in the long term by increasing our knowledge of the underlying physical processes of power generation in organic solar cells and identifying concrete steps to optimize the cells through methods such as the implementation of sophisticated surface structures and frequency-converting nanoparticles or the use of novel donor and acceptor molecules.
Publications
- P3HT:DiPBI bulk heterojunction solar cells: morphology and electronic structure probed by multiscale simulation and UV/vis spectroscopy, Phys. Chem. Chem. Phys., 18 (2016) 6217
T. Winands, M. Böckmann, T. Schemme, P.-M. T. Ly, D. H. de Jong, Z. Wang, C. Denz, A. Heuer, N. L. Doltsinis
(See online at https://doi.org/10.1039/c5cp06704a) - Creating aperiodic photonic structures by synthesized Mathieu-Gauss beams, Phys. Rev. A 96 (2017) 023840
J. M. Vasiljević, A. Zannotti, D. V. Timotijević, C. Denz, D. M. Jović Savić
(See online at https://doi.org/10.1103/PhysRevA.96.023840) - Decatwistacene with a 170◦ Torsion, Angew. Chem. Int. Ed., 56 (2017) 15373–15377
W. Fan, T. Winands, N. L. Doltsinis, Y. Li, Z. Wang
(See online at https://doi.org/10.1002/anie.201709342) - Observation of transverse coherent backscattering in disordered photonic structures, Scientific Reports 7 (2017) 10439
M. Boguslawski, S. Brake, D. Leykam, A. S. Desyatnikov, C. Denz
(See online at https://doi.org/10.1038/s41598-017-10852-7) - Roadmap on structured light, J. Opt. 19 (2017) 013001
H. Rubinsztein-Dunlop, A. Forbes, M. V. Berry, M. R. Dennis, D. L. Andrews, M. Mansuripur, C. Alpmann, C. Denz, et al.
(See online at https://doi.org/10.1088/2040-8978/19/1/013001) - Hexacene Diimides, J. Am. Chem. Soc., 140 (2018) 12175-12180
X. Cui, T. Winands, T. Koch, Y. Li, L. Zhang, N.L. Doltsinis, Z. Wang
(See online at https://doi.org/10.1021/jacs.8b07305) - Nanographene Imides Featuring Dual-Core Sixfold [5]Helicenes, Angew. Chem. 58 (2019) 178-183
G. Liu, T. Koch, Y. Li, N. L. Doltsinis, Z. Wang
(See online at https://doi.org/10.1002/anie.201810734) - Exciton Transfer Free Energy from Car-Parrinello Molecular Dynamics, Phys. Chem. Chem. Phys., 22 (2020) 10526-10535
C. Schwermann, N. L. Doltsinis
(See online at https://doi.org/10.1039/C9CP06419B) - Aperiodic biomimetic Vogel spirals as diffractive optical elements for tailored light distribution in functional polymer layers, J. Opt. 23 (2021) 065401
M. Merkel, T. Schemme, C. Denz
(See online at https://doi.org/10.1088/2040-8986/abf8cc) - Multiscale modelling of charge transport in P3HT:DIPBI bulk heterojunction organic solar cells, Phys. Chem. Chem. Phys., 23 (2021) 12233–12250
T. Koch, J. Bachmann, T. Lettmann, N. L. Doltsinis
(See online at https://doi.org/10.1039/D1CP00674F)
