214
S. Izawa
thereby reducing the LUMO-LUMO or HOMO-HOMO offset between the donor
and the acceptor. Third, crystallinity should be increased to reduce the trap state near
the D/A interface. In Sect. 8.3.6, it was shown that the energy difference between E
opt
g
and E CT could be reduced to 0.06 eV, and in Sect. 8.3.5 that the energy difference
between E CT and eV OC could be reduced to 0.26 eV. By combining these two effects,
a very small V OC loss of less than 0.3 eV, similar to that in inorganic SCs, can be
achieved. Our research has revealed that controlling the D/A interfacial structure can
reduce V OC loss in OSCs, and we expect that this research will provide a route to
achieving high power conversion efficiencies in OSCs, close to those in the efficient
inorganic SCs.
Acknowledgments The research works presented in this chapter were conducted with by Prof.
Hiramoto, Dr. Shintaku, Dr. Kikuchi, Mr. Lee, and Mr. Perrot in Institute for Molecular Science,
and Dr. Tajima and Dr. Nakano in Riken, and Prof. Takahashi and Prof. Fujimoto in Shizuoka
University. They were partly supported by the JSPS KAKENHI (Grant-in-Aid for Research Activity
Start-up, No. 16H07421 and for Young Scientist, 18K14115), the foundation of Chubu Science and
Technology Center and the Mazda foundation.
References
1. Dou, L., You, J., Hong, Z., Xu, Z., Li, G., Street, R.A., Yang, Y.: 25th Anniversary article—a
decade of organic/polymeric photovoltaic research. Adv. Mater. 25, 6642–6671 (2013)
2. Liu, L., Kan, Y., Gao, K., Wang, J., Zhao, M., Chen, H., Zhao, C., Jiu, T., Jen, A.K.Y., Li,
Y.: Graphdiyne derivative as multifunctional solid additive in binary organic solar cells with
17.3% efficiency and high reproductivity. Adv. Mater. 32, 1907604 (2020)
3. Hiramoto, M., Fujiwara, H., Yokoyama, M.: Three-layered organic solar cell with a photoactive
interlayer of codeposited pigment. Appl. Phys. Lett. 58, 1062–1064 (1991)
4. Yu, G., Gao, J., Hummelen, J.C., Wudl, F., Heeger, A.J.: Polymer photovoltaic cells: enhanced
efficiencies via a network of internal donor-acceptor heterojunctions. Science 270, 1789–1791
(1995)
5. Lu, L., Zheng, T., Wu, Q., Schneider, A. M., Zhao, D., Yu, L.: Recent advances in bulk
heterojunction polymer solar cells. Chem. Rev. 115, 12666–12731 (2015)
6. Hou, J., Inganäs, O., Friend, R., Gao, F.: Organic solar cells based on non-fullerene acceptors.
Nat. Mater. 17, 119–128 (2018)
7. National Renewable Energy Laboratory, Best Research-Cell Efficiency Chart (2019)
8. Baran, D., Gasparini, N., Wadsworth, A., Tan, C.H., Wehbe, N., Song, X., Hamid, Z., Zhang, W.,
Neophytou, M., Kirchartz, T., Brabec, C.J., Durrant, J.R., McCulloch, I.: Robust nonfullerene
solar cells approaching unity external quantum efficiency enabled by suppression of geminate
recombination. Nat. Commun. 9, 2059 (2018)
9. Park, S.H., Roy, A., Beaupré, S., Cho, S., Coates, N., Moon, J.S., Moses, D., Leclerc, M., Lee,
K., Heeger, A.J.: Bulk heterojunction solar cells with internal quantum efficiency approaching
100%. Nat. Photon. 3, 297–295 (2009)
10. Clarke, T.M., Durrant, J.R.: Charge photogeneration in organic solar cells. Chem. Rev. 110,
6736–6767 (2010)
11. Knupfer, M.: Exciton binding energies in organic semiconductors. Appl. Phys. A 77, 623–626
(2003)
12. Kroeze, J.E., Savenije, T.J., Vermeulen, M.J.W., Warman, J.M.: Contactless determination
of the photoconductivity action spectrum, exciton diffusion length, and charge separation
efficiency in polythiophene-sensitized TiO 2 bilayers. J. Phys. Chem. B 107, 7696–7705 (2003)
S. Izawa
thereby reducing the LUMO-LUMO or HOMO-HOMO offset between the donor
and the acceptor. Third, crystallinity should be increased to reduce the trap state near
the D/A interface. In Sect. 8.3.6, it was shown that the energy difference between E
opt
g
and E CT could be reduced to 0.06 eV, and in Sect. 8.3.5 that the energy difference
between E CT and eV OC could be reduced to 0.26 eV. By combining these two effects,
a very small V OC loss of less than 0.3 eV, similar to that in inorganic SCs, can be
achieved. Our research has revealed that controlling the D/A interfacial structure can
reduce V OC loss in OSCs, and we expect that this research will provide a route to
achieving high power conversion efficiencies in OSCs, close to those in the efficient
inorganic SCs.
Acknowledgments The research works presented in this chapter were conducted with by Prof.
Hiramoto, Dr. Shintaku, Dr. Kikuchi, Mr. Lee, and Mr. Perrot in Institute for Molecular Science,
and Dr. Tajima and Dr. Nakano in Riken, and Prof. Takahashi and Prof. Fujimoto in Shizuoka
University. They were partly supported by the JSPS KAKENHI (Grant-in-Aid for Research Activity
Start-up, No. 16H07421 and for Young Scientist, 18K14115), the foundation of Chubu Science and
Technology Center and the Mazda foundation.
References
1. Dou, L., You, J., Hong, Z., Xu, Z., Li, G., Street, R.A., Yang, Y.: 25th Anniversary article—a
decade of organic/polymeric photovoltaic research. Adv. Mater. 25, 6642–6671 (2013)
2. Liu, L., Kan, Y., Gao, K., Wang, J., Zhao, M., Chen, H., Zhao, C., Jiu, T., Jen, A.K.Y., Li,
Y.: Graphdiyne derivative as multifunctional solid additive in binary organic solar cells with
17.3% efficiency and high reproductivity. Adv. Mater. 32, 1907604 (2020)
3. Hiramoto, M., Fujiwara, H., Yokoyama, M.: Three-layered organic solar cell with a photoactive
interlayer of codeposited pigment. Appl. Phys. Lett. 58, 1062–1064 (1991)
4. Yu, G., Gao, J., Hummelen, J.C., Wudl, F., Heeger, A.J.: Polymer photovoltaic cells: enhanced
efficiencies via a network of internal donor-acceptor heterojunctions. Science 270, 1789–1791
(1995)
5. Lu, L., Zheng, T., Wu, Q., Schneider, A. M., Zhao, D., Yu, L.: Recent advances in bulk
heterojunction polymer solar cells. Chem. Rev. 115, 12666–12731 (2015)
6. Hou, J., Inganäs, O., Friend, R., Gao, F.: Organic solar cells based on non-fullerene acceptors.
Nat. Mater. 17, 119–128 (2018)
7. National Renewable Energy Laboratory, Best Research-Cell Efficiency Chart (2019)
8. Baran, D., Gasparini, N., Wadsworth, A., Tan, C.H., Wehbe, N., Song, X., Hamid, Z., Zhang, W.,
Neophytou, M., Kirchartz, T., Brabec, C.J., Durrant, J.R., McCulloch, I.: Robust nonfullerene
solar cells approaching unity external quantum efficiency enabled by suppression of geminate
recombination. Nat. Commun. 9, 2059 (2018)
9. Park, S.H., Roy, A., Beaupré, S., Cho, S., Coates, N., Moon, J.S., Moses, D., Leclerc, M., Lee,
K., Heeger, A.J.: Bulk heterojunction solar cells with internal quantum efficiency approaching
100%. Nat. Photon. 3, 297–295 (2009)
10. Clarke, T.M., Durrant, J.R.: Charge photogeneration in organic solar cells. Chem. Rev. 110,
6736–6767 (2010)
11. Knupfer, M.: Exciton binding energies in organic semiconductors. Appl. Phys. A 77, 623–626
(2003)
12. Kroeze, J.E., Savenije, T.J., Vermeulen, M.J.W., Warman, J.M.: Contactless determination
of the photoconductivity action spectrum, exciton diffusion length, and charge separation
efficiency in polythiophene-sensitized TiO 2 bilayers. J. Phys. Chem. B 107, 7696–7705 (2003)