Novel Molecular Doping Mechanism for n-Doping of SnO2 via Triphenylphosphine Oxide and Its Effect on Perovskite Solar Cells

Bao Tu; Yangfan Shao; Wei Chen; Yinghui Wu; Xin Li; Yanling He; Jiaxing Li; Fangzhou Liu; Zheng Zhang; Yi Lin; Xiaoqi Lan; Leiming Xu; Xingqiang Shi; Alan Man Ching Ng; Haifeng Li; Lung Wa Chung; Aleksandra B Djurišić; Zhubing He

doi:10.1002/adma.201805944

Novel Molecular Doping Mechanism for n-Doping of SnO₂ via Triphenylphosphine Oxide and Its Effect on Perovskite Solar Cells

Adv Mater. 2019 Apr;31(15):e1805944. doi: 10.1002/adma.201805944. Epub 2019 Jan 30.

Authors

Bao Tu^{1

2}, Yangfan Shao^{2

3}, Wei Chen^{1

4}, Yinghui Wu¹, Xin Li^{1

5}, Yanling He^{1

3}, Jiaxing Li^{1

3}, Fangzhou Liu⁴, Zheng Zhang¹, Yi Lin¹, Xiaoqi Lan¹, Leiming Xu¹, Xingqiang Shi³, Alan Man Ching Ng³, Haifeng Li², Lung Wa Chung⁵, Aleksandra B Djurišić⁴, Zhubing He¹

Affiliations

¹ Department of Materials Science and Engineering, Shenzhen Key Laboratory of Full Spectral Solar Electricity Generation (FSSEG), Southern University of Science and Technology, No. 1088, Xueyuan Rd., Shenzhen, 518055, Guangdong, China.
² Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, 999078, Macau SAR, China.
³ Department of Physics, Southern University of Science and Technology, No. 1088, Xueyuan Rd., Shenzhen, 518055, Guangdong, China.
⁴ Department of Physics, The University of Hong Kong, Pokfulam, 999077, Hong Kong SAR, China.
⁵ Department of Chemistry, Southern University of Science and Technology, No. 1088, Xueyuan Rd., Shenzhen, 518055, Guangdong, China.

PMID: 30697836
DOI: 10.1002/adma.201805944

Abstract

Molecular doping of inorganic semiconductors is a rising topic in the field of organic/inorganic hybrid electronics. However, it is difficult to find dopant molecules which simultaneously exhibit strong reducibility and stability in ambient atmosphere, which are needed for n-type doping of oxide semiconductors. Herein, successful n-type doping of SnO₂ is demonstrated by a simple, air-robust, and cost-effective triphenylphosphine oxide molecule. Strikingly, it is discovered that electrons are transferred from the R3P⁺ O^- σ-bond to the peripheral tin atoms other than the directly interacted ones at the surface. That means those electrons are delocalized. The course is verified by multi-photophysical characterizations. This doping effect accounts for the enhancement of conductivity and the decline of work function of SnO₂ , which enlarges the built-in field from 0.01 to 0.07 eV and decreases the energy barrier from 0.55 to 0.39 eV at the SnO₂ /perovskite interface enabling an increase in the conversion efficiency of perovskite solar cells from 19.01% to 20.69%.

Keywords: SnO2; delocalized electrons; molecular doping; n-type; perovskite solar cells.

Abstract

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