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 - Publisher Copyright:
© 2019 American Chemical Society.
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 -