Shigeo Maruyama1 2

1, The University of Tokyo, Tokyo, , Japan
2, AIST, Tsukuba, , Japan

Single-walled carbon nanotubes (SWNT), graphene, and fullerene (C60 and PCBM) would be very efficiently used in lead halide Perovskite solar cells. A film of SWNTs or graphene can be flexible and stretchable transparent-conductive layer. At the same time, this film can be carrier-selective layers, i.e., electron-blocking-layers or hole-blocking-layers, by using adequate polymer-doping. Based on our experiences of using nanotube films for CNT-Si solar cells and organic polymer solar cells [1,2], we have extended the application of SWNT films for organic-inorganic Perovskite solar cells. We have demonstrated the replacement of ITO in inverted-type perovskite solar cells, SWNTs/PEDOT:PSS/CH3NH3PbI3/PCBM/Al [3]. The flexible application on polyethylene terephthalate (PET) is also demonstrated [3]. Replacement of electron-blocking-layer and metal electrode in normal-type perovskite solar cells is demonstrated as well. They show high power conversion efficiency (PCE), cost-efficiency, and higher stability. Those devices can have comparable PCE as the conventional design with organic electron-blocking layer and top metal electrode. The normal-type perovskite solar cell, composed of ITO/C60/CH3NH3PbI3/SWNTs, can achieve a PCE of 17 % with spiro-MeOTAD as dopant to SWNTs [4]. This structure with a perovskite layer sandwiched by C60 and SWNTs can lead to the solar cells without hysteresis and with much improved air-stability [4]. The effective passivation of the degradation of perovskite material by moisture can be achieved with C60 and SWNTs [4]. More recent configuration is using a film of SWNTs for both anode and cathode electrode [5]. With adequate polymer-doping, we can fabricate Perovskite solar cells without ITO and metal electrode. Finally, SWNT film and graphene are compared as flexible transparent electrode of inverted Perovskite solar cells [6].
This work was supported by JSPS KAKENHI Grant Numbers JP25107002 and JP15H05760.

[1] I. Jeon, K. Cui, T. Chiba, A. Anisimov, A. Nasibulin, E. Kauppinen, S. Maruyama, Y. Matsuo, J. Am. Chem. Soc., 137, 7982 (2015).
[2] I. Jeon, C. Delacou, A. Kaskela, E. I. Kauppinen, S. Maruyama, Y. Matsuo, Sci. Rep. 6, 31348 (2016).
[3] I. Jeon, T. Chiba, C. Delacou, Y. Guo, A. Kaskela, O. Reynaud, E. I. Kauppinen, S. Maruyama, Y. Matsuo, Nano Lett. 15, 6665 (2015).
[4] N. Ahn, I. Jeon, J. Yoon, E. I. Kauppinen, Y. Matsuo, S. Maruyama, M. Choi, submitted.
[5] I. Jeon, S. Seo, Y. Sato, C. Delacou, A. Anisimov, K. Suenaga, E. I. Kauppinen, S. Maruyama, Y. Matsuo, J. Phys. Chem. C, (2017) [DOI: 10.1021/acs.jpcc.7b10334].
[6] I. Jeon, J. Yoon, N. Ahn, M. Atwa, C. Delacou, A. Anisimov, E. Kauppinen, M. Choi, S. Maruyama, Y. Matsuo, J. Phys. Chem. Lett., 8 (2017), 5395.