TY - JOUR
T1 - Origin of Extended UV Stability of 2D Atomic Layer Titania-Based Perovskite Solar Cells Unveiled by Ultrafast Spectroscopy
AU - Thilakan, Anusha Puliparambil
AU - Li, Jia Xing
AU - Chen, Tzu Pei
AU - Li, Shao Sian
AU - Chen, Chun Wei
AU - Osada, Minoru
AU - Tsukagoshi, Kazuhito
AU - Sasaki, Takayoshi
AU - Yabushita, Atsushi
AU - Wu, Kaung Hsiung
AU - Luo, Chih Wei
N1 - Funding Information:
This work was supported by the Ministry of Science and Technology, Taiwan (grant nos. 106-2119-M-009-013-FS, 106-2628-M-009-003-MY3, and 107-2119-M-009-010-MY2). This work was also financially supported by the Center for Emergent Functional Matter Science of National Chiao Tung University from The Featured Areas Research Center Program, the Research Team of Photonic Technologies and Intelligent Systems at NCTU and Taipei Medical University (grant nos DP2-107-21121-O-06 and TMU107-AE1-B10) within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan.
PY - 2019/6/19
Y1 - 2019/6/19
N2 - The inherent instability of UV-induced degradation in TiO2-based perovskite solar cells was largely improved by replacing the anatase-phase compact TiO2 layer with an atomic sheet transport layer (ASTL) of two-dimensional (2D) Ti1-δO2. The vital role of microscopic carrier dynamics that govern the UV stability of perovskite solar cells was comprehensively examined in this work by performing time-resolved pump-probe spectroscopy. In conventional perovskite solar cells, the presence of a UV-active oxygen vacancy in compact TiO2 prohibits current generation by heavily trapping electrons after UV degradation. Conversely, the dominant vacancy type in the 2D Ti1-δO2 ASTL is a titanium vacancy, which is a shallow acceptor and is not UV-sensitive. Therefore, it significantly suppresses carrier recombination and extends UV stability in perovskite solar cells with a 2D Ti1-δO2 ASTL. Other carrier dynamics, such as electron diffusion, electron injection, and hot hole transfer processes, were found to be less affected by UV irradiation. Quantitative pump-probe data clearly show a correlation between the carrier dynamics and UV aging of perovskite solar cells, thus providing a profound insight into the factors driving UV-induced degradation in perovskite solar cells and the origin of its performance.
AB - The inherent instability of UV-induced degradation in TiO2-based perovskite solar cells was largely improved by replacing the anatase-phase compact TiO2 layer with an atomic sheet transport layer (ASTL) of two-dimensional (2D) Ti1-δO2. The vital role of microscopic carrier dynamics that govern the UV stability of perovskite solar cells was comprehensively examined in this work by performing time-resolved pump-probe spectroscopy. In conventional perovskite solar cells, the presence of a UV-active oxygen vacancy in compact TiO2 prohibits current generation by heavily trapping electrons after UV degradation. Conversely, the dominant vacancy type in the 2D Ti1-δO2 ASTL is a titanium vacancy, which is a shallow acceptor and is not UV-sensitive. Therefore, it significantly suppresses carrier recombination and extends UV stability in perovskite solar cells with a 2D Ti1-δO2 ASTL. Other carrier dynamics, such as electron diffusion, electron injection, and hot hole transfer processes, were found to be less affected by UV irradiation. Quantitative pump-probe data clearly show a correlation between the carrier dynamics and UV aging of perovskite solar cells, thus providing a profound insight into the factors driving UV-induced degradation in perovskite solar cells and the origin of its performance.
KW - electron transport layer
KW - perovskite solar cell
KW - pump-probe technique
KW - two-dimensional metal oxide
KW - ultrafast mechanism
KW - UV degradation
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U2 - 10.1021/acsami.9b02434
DO - 10.1021/acsami.9b02434
M3 - Article
C2 - 31135127
AN - SCOPUS:85067434709
SN - 1944-8244
VL - 11
SP - 21473
EP - 21480
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 24
ER -