Stable and Efficient Organo-Metal Halide Hybrid Perovskite Solar Cells via π-Conjugated Lewis Base Polymer Induced Trap Passivation and Charge Extraction

Ping-Li Qin; Guang Yang; Zhi-Wei Ren; Sin Hang Cheung; Shu Kong So; Li Chen; Jianhua Hao; Jianhui Hou; Gang Li

doi:10.1002/adma.201706126

Stable and Efficient Organo-Metal Halide Hybrid Perovskite Solar Cells via π-Conjugated Lewis Base Polymer Induced Trap Passivation and Charge Extraction

Adv Mater. 2018 Mar;30(12):e1706126. doi: 10.1002/adma.201706126. Epub 2018 Feb 7.

Authors

Ping-Li Qin^{1

2}, Guang Yang^{1

3}, Zhi-Wei Ren¹, Sin Hang Cheung⁴, Shu Kong So⁴, Li Chen⁵, Jianhua Hao⁵, Jianhui Hou⁶, Gang Li¹

Affiliations

¹ Department of Electronic and Information Engineering, Hong Kong Polytechnic University, Hong Hum, Kowloon, Hong Kong SAR, China.
² Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong.
³ School of Science, Wuhan Institute of Technology, Wuhan, Hubei, 430073, China.
⁴ Department of Applied Physics, Hong Kong Polytechnic University, Hong Hum, Kowloon, Hong Kong SAR, China.
⁵ Institute of Chemistry, Chinese Academy of Science, Beijing, 100190, China.
⁶ School of Physics and Technology, Wuhan University, Wuhan, Hubei, China.

PMID: 29411431
DOI: 10.1002/adma.201706126

Abstract

High-quality pinhole-free perovskite film with optimal crystalline morphology is critical for achieving high-efficiency and high-stability perovskite solar cells (PSCs). In this study, a p-type π-conjugated polymer poly[(2,6-(4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)-benzo[1,2-b:4,5-b'] dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl) benzo[1',2'-c:4',5'-c'] dithiophene-4,8-dione))] (PBDB-T) is introduced into chlorobenzene to form a facile and effective template-agent during the anti-solvent process of perovskite film formation. The π-conjugated polymer PBDB-T is found to trigger a heterogeneous nucleation over the perovskite precursor film and passivate the trap states of the mixed perovskite film through the formation of Lewis adducts between lead and oxygen atom in PBDB-T. The p-type semiconducting and hydrophobic PBDB-T polymer fills in the perovskite grain boundaries to improve charge transfer for better conductivity and prevent moisture invasion into the perovskite active layers. Consequently, the PSCs with PBDB-T modified anti-solvent processing leads to a high-efficiency close to 20%, and the devices show excellent stability, retaining about 90% of the initial power conversion efficiency after 150 d storage in dry air.

Keywords: charge extraction; grain boundary; hydrophobicity; perovskite solar cells; trap passivation.