Key factors to eliminate the I-V hysteresis of lead halide perovskite solar cells

Zeguo Tang^a, Takeru Bessho^a, Fumiyasu Awai^b, Takumi Kinoshita^a, Haibin Wang^a, Masato Maitani^a, Ryota Jono^a, Jotaro Nakazaki^a, Takaya Kubo^a, Satoshi Uchida^c, Hiroshi Segawa^a^,^b^,^c

^aResearch Center for Advanced Science and Technology (RCAST), The University of Tokyo, Japan, Japan

^bUniversity of Tokyo, Japan, Japan

^cKomaba Organization for Educational Excellence (KOMEX), The University of Tokyo, Japan., 3-chōme-8-1 Komaba, Meguro City, Tōkyō-to 153-0041, Japón, Meguro City, Japan

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
Proceedings of International Conference Asia-Pacific Hybrid and Organic Photovoltaics 2018 (AP-HOPV18)

Kitakyūshū-shi, Japan, 2018 January 28th - 30th

Organizers: Shuzi Hayase, Juan Bisquert and Hiroshi Segawa

Poster, Zeguo Tang, 137
Publication date: 27th October 2017

In the case of the perovskite solar cells, the interface between the perovskite absorber and electron transport layer (ETL) is crucial to suppress the hysteresis in I-V curves [1, 2]. The barrier at the perovskite/TiO₂ interface will retard the electron transport [3] from perovskite to TiO₂, and the accumulation of electrons results in capacitance [4].

In this study, we prepared perovskite solar cells without I-V hysteresis by the incorporation of potassium cation (K⁺) in the perovskite absorber [5]. The K⁺ incorporation results in the upshifting of conduction band minimum (CBM) and minimizing the potential barrier at the interface of perovskite/TiO₂. Simultaneously, the incorporation of K⁺ passivates the defects at the grain boundaries, which also benefits the carrier collection. All the findings demonstrate that not only the barrier at perovskite/TiO₂ but also the defects in perovskite absorber play the critical role in the I-V hysteresis. Consequently, hysteresis-free perovskite solar cells having the over 20% efficiency were constructed by the use of the K⁺-doped perovskite.

[1] W. Tress, J. P. C. Baena, M. Graetzel et al., Adv. Energy Mater. 2016, 6, 1600396.

[2] H. Tan, A. Jain, E. H. Sargent et al., Science 10.1126/science.aai9081 (2017).

[3] J. P. C. Baena, L. Steier, A. Hagfeldt et al., Energy Environ. Sci., 2015, 8, 2928-2934.

[4] L. Cojocaru, S. Uchida, H. Segawa et al., Chem. Lett. 2015, 44, 1750–1752.

[5] Z. Tang, T. Bessho, F. Awai, T. Kinoshita, M. M. Maitani, R. Jono, T. N. Murakami, H. Wang, T. Kubo,S. Uchida, H. Segawa, Sci. Rep. 2017, 7, 12183.

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