Crystal face dependent charge carrier extraction in TiO2/perovskite heterojunctions

Bin Du; Qi Wei; Yongqing Cai; Tanghao Liu; Bo Wu; Ying Li; Yonghua Chen; Yingdong Xia; Guichuan Xing; Wei Huang

doi:10.1016/j.nanoen.2019.104227

Crystal face dependent charge carrier extraction in TiO₂/perovskite heterojunctions

Bin Du, Qi Wei, Yongqing Cai, Tanghao Liu, Bo Wu, Ying Li, Yonghua Chen, Yingdong Xia^*, Guichuan Xing^*, Wei Huang^*

^*Corresponding author for this work

Department of Physics

Research output: Contribution to journal › Journal article › peer-review

24 Citations (Scopus)

Abstract

Solar cells based on metal-halide perovskite/TiO₂ heterojunction have demonstrated exceptional high power conversion efficiencies. However, the electron extractor TiO₂ is typically a polycrystalline film processed with solution methods. The crystal face dependent electron extraction from perovskite to this TiO₂ film is still unclear, which is essential for the device performance further optimization. Herein, the ultrafast charge carrier dynamics in CH₃NH₃PbI₃/TiO₂ heterojunctions with rutile TiO₂ single crystals terminated at (100), (001) and (110) faces were systematically investigated. Our results clearly show that the charge carrier extraction from perovskite to TiO₂ is strongly dependent on the TiO₂ crystal face. The (100) face shows the best charge carrier extraction performance with an electron extraction efficiency over 98%. In contrast, the (001) face demonstrates an electron extraction efficiency less than 40%. The hot electron extraction from photo-excited perovskite to TiO₂ has also been clearly revealed with transient absorption. The first-principle density function theory calculations indicate that the electron transfer from CH₃NH₃PbI₃ to rutile TiO₂ is more energetically favoured for the (100) and (110) faces than for the (001) face. These findings reveal the hidden role of the TiO₂ crystal facets in electron extraction and its impact on the perovskite solar cell efficiency.

Original language	English
Article number	104227
Journal	Nano Energy
Volume	67
DOIs	https://doi.org/10.1016/j.nanoen.2019.104227
Publication status	Published - Jan 2020

User-Defined Keywords

Electron transfer
Heterojunctions
Hot electron
Perovskites solar cells
TiO

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This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.nanoen.2019.104227

Cite this

@article{5835154dafec483ea3b0d1c27c8024c5,

title = "Crystal face dependent charge carrier extraction in TiO2/perovskite heterojunctions",

abstract = "Solar cells based on metal-halide perovskite/TiO2 heterojunction have demonstrated exceptional high power conversion efficiencies. However, the electron extractor TiO2 is typically a polycrystalline film processed with solution methods. The crystal face dependent electron extraction from perovskite to this TiO2 film is still unclear, which is essential for the device performance further optimization. Herein, the ultrafast charge carrier dynamics in CH3NH3PbI3/TiO2 heterojunctions with rutile TiO2 single crystals terminated at (100), (001) and (110) faces were systematically investigated. Our results clearly show that the charge carrier extraction from perovskite to TiO2 is strongly dependent on the TiO2 crystal face. The (100) face shows the best charge carrier extraction performance with an electron extraction efficiency over 98%. In contrast, the (001) face demonstrates an electron extraction efficiency less than 40%. The hot electron extraction from photo-excited perovskite to TiO2 has also been clearly revealed with transient absorption. The first-principle density function theory calculations indicate that the electron transfer from CH3NH3PbI3 to rutile TiO2 is more energetically favoured for the (100) and (110) faces than for the (001) face. These findings reveal the hidden role of the TiO2 crystal facets in electron extraction and its impact on the perovskite solar cell efficiency.",

keywords = "Electron transfer, Heterojunctions, Hot electron, Perovskites solar cells, TiO",

author = "Bin Du and Qi Wei and Yongqing Cai and Tanghao Liu and Bo Wu and Ying Li and Yonghua Chen and Yingdong Xia and Guichuan Xing and Wei Huang",

note = "Funding Information: This work acknowledges the financial support from Macau Science and Technology Development Fund ( FDCT-116/2016/A3 , FDCT-091/2017/A2 ), Research Grant ( SRG2016-00087-FST , MYRG2018-00148-IAPME ) from University of Macau, the Natural Science Foundation of China ( 61904152 , 91733302 , 61605073 , 2015CB932200 ), and the Young 1000 Talents Global Recruitment Program of China. This work was also financially supported by the National Basic Research Program of China, Fundamental Studies of Perovskite Solar Cells (Grant 2015CB932200 ), the Natural Science Foundation of China (Grants 51602149 , 61705102 ), Natural Science Foundation of Jiangsu Province, China (Grants BK20161011 and BK20161010 ), Young 1000 Talents Global Recruitment Program of China ( 51235086 ), Jiangsu Specially-Appointed Professor program, “Six talent peaks” Project in Jiangsu Province, China. This work financially supported by “the Fundamental Research Funds for the Central Universities . Qi WEI thanks the project funded by China Postdoctoral Science Foundation ( 2019M653721 ). Bo Wu acknowledges the support from the National Natural Science Foundation of China (grant No. 51802331 ), Guangdong Provincial Key Laboratory of Optical Information Materials and Technology (Grant No. 2017B030301007 ) and the 111 Project. Publisher Copyright: {\textcopyright} 2019",

year = "2020",

month = jan,

doi = "10.1016/j.nanoen.2019.104227",

language = "English",

volume = "67",

journal = "Nano Energy",

issn = "2211-2855",

publisher = "Elsevier B.V.",

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TY - JOUR

T1 - Crystal face dependent charge carrier extraction in TiO2/perovskite heterojunctions

AU - Du, Bin

AU - Wei, Qi

AU - Cai, Yongqing

AU - Liu, Tanghao

AU - Wu, Bo

AU - Li, Ying

AU - Chen, Yonghua

AU - Xia, Yingdong

AU - Xing, Guichuan

AU - Huang, Wei

N1 - Funding Information: This work acknowledges the financial support from Macau Science and Technology Development Fund ( FDCT-116/2016/A3 , FDCT-091/2017/A2 ), Research Grant ( SRG2016-00087-FST , MYRG2018-00148-IAPME ) from University of Macau, the Natural Science Foundation of China ( 61904152 , 91733302 , 61605073 , 2015CB932200 ), and the Young 1000 Talents Global Recruitment Program of China. This work was also financially supported by the National Basic Research Program of China, Fundamental Studies of Perovskite Solar Cells (Grant 2015CB932200 ), the Natural Science Foundation of China (Grants 51602149 , 61705102 ), Natural Science Foundation of Jiangsu Province, China (Grants BK20161011 and BK20161010 ), Young 1000 Talents Global Recruitment Program of China ( 51235086 ), Jiangsu Specially-Appointed Professor program, “Six talent peaks” Project in Jiangsu Province, China. This work financially supported by “the Fundamental Research Funds for the Central Universities . Qi WEI thanks the project funded by China Postdoctoral Science Foundation ( 2019M653721 ). Bo Wu acknowledges the support from the National Natural Science Foundation of China (grant No. 51802331 ), Guangdong Provincial Key Laboratory of Optical Information Materials and Technology (Grant No. 2017B030301007 ) and the 111 Project. Publisher Copyright: © 2019

PY - 2020/1

Y1 - 2020/1

N2 - Solar cells based on metal-halide perovskite/TiO2 heterojunction have demonstrated exceptional high power conversion efficiencies. However, the electron extractor TiO2 is typically a polycrystalline film processed with solution methods. The crystal face dependent electron extraction from perovskite to this TiO2 film is still unclear, which is essential for the device performance further optimization. Herein, the ultrafast charge carrier dynamics in CH3NH3PbI3/TiO2 heterojunctions with rutile TiO2 single crystals terminated at (100), (001) and (110) faces were systematically investigated. Our results clearly show that the charge carrier extraction from perovskite to TiO2 is strongly dependent on the TiO2 crystal face. The (100) face shows the best charge carrier extraction performance with an electron extraction efficiency over 98%. In contrast, the (001) face demonstrates an electron extraction efficiency less than 40%. The hot electron extraction from photo-excited perovskite to TiO2 has also been clearly revealed with transient absorption. The first-principle density function theory calculations indicate that the electron transfer from CH3NH3PbI3 to rutile TiO2 is more energetically favoured for the (100) and (110) faces than for the (001) face. These findings reveal the hidden role of the TiO2 crystal facets in electron extraction and its impact on the perovskite solar cell efficiency.

AB - Solar cells based on metal-halide perovskite/TiO2 heterojunction have demonstrated exceptional high power conversion efficiencies. However, the electron extractor TiO2 is typically a polycrystalline film processed with solution methods. The crystal face dependent electron extraction from perovskite to this TiO2 film is still unclear, which is essential for the device performance further optimization. Herein, the ultrafast charge carrier dynamics in CH3NH3PbI3/TiO2 heterojunctions with rutile TiO2 single crystals terminated at (100), (001) and (110) faces were systematically investigated. Our results clearly show that the charge carrier extraction from perovskite to TiO2 is strongly dependent on the TiO2 crystal face. The (100) face shows the best charge carrier extraction performance with an electron extraction efficiency over 98%. In contrast, the (001) face demonstrates an electron extraction efficiency less than 40%. The hot electron extraction from photo-excited perovskite to TiO2 has also been clearly revealed with transient absorption. The first-principle density function theory calculations indicate that the electron transfer from CH3NH3PbI3 to rutile TiO2 is more energetically favoured for the (100) and (110) faces than for the (001) face. These findings reveal the hidden role of the TiO2 crystal facets in electron extraction and its impact on the perovskite solar cell efficiency.

KW - Electron transfer

KW - Heterojunctions

KW - Hot electron

KW - Perovskites solar cells

KW - TiO

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DO - 10.1016/j.nanoen.2019.104227

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VL - 67

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