Title: GeI₂ Additive for High Optoelectronic Quality CsPbI₃ Quantum Dots and Their Application in Photovoltaic Devices

Abstract

Trioctylphosphine (TOP)-based syntheses of CsPbI₃ perovskite quantum dots (QDs) yield unprecedented high photoluminescence quantum yield (PL QY), lower Stokes shifts, and longer carrier lifetimes due to their enhanced crystallinity. This synthetic route relies on a heavily Pb-rich condition or a large Pb:Cs molar ratio in precursor solution to produce QDs with appropriate stoichiometry as well as to guarantee a good colloidal stability. The high Pb condition is achieved by a high concentration of PbI₂ prepared in TOP. Here we find such Pb-rich strategies can be avoided by providing additional iodine ions using other metal halide salts. In particular GeI₂, which contrary to PbI₂, readily dissolves in TOP. CsPbI₃ QDs prepared using PbI₂/GeI₂ combination show near-unity PL QY and improved chemical stability compared to the previous synthetic route. Furthermore, we find no sign of Ge incorporation in the QDs (compositionally or energetically). The ensuing QD solar cells deliver power conversion efficiency of 12.15% and retain 85% of its peak performance after storage over 90 days. The PbI₂/GeI₂ dual-source iodine synthetic approach presented here represents a more rational and robust route to high-quality CsPbI₃ QDs. to guarantee a good colloidal stability. The high Pb condition is achieved by a high concentration ofmore » PbI2 prepared in TOP. Here we find such Pb-rich strategies can be avoided by providing additional iodine ions using other metal halide salts. In particular GeI₂, which contrary to PbI₂, readily dissolves in TOP. CsPbI₃ QDs prepared using PbI₂/GeI₂ combination show near-unity PL QY and improved chemical stability compared to the previous synthetic route. Furthermore, we find no sign of Ge incorporation in the QDs (compositionally or energetically). The ensuing QD solar cells deliver power conversion efficiency of 12.15% and retain 85% of its peak performance after storage over 90 days. The PbI₂/GeI₂ dual-source iodine synthetic approach presented here represents a more rational and robust route to high-quality CsPbI₃ QDs.« less

Authors:

Liu, Feng ^[1]; Ding, Chao ^[1]; Zhang, Yaohong ^[1]; Kamisaka, Taichi ^[1]; Zhao, Qian ^[2]; Luther, Joseph M  ^[3];

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Toyoda, Taro ^[1]; Hayase, Shuzi ^[4]; Minemoto, Takashi ^[5]; Yoshino, Kenji ^[6]; Zhang, Bing ^[7]; Dai, Songyuan ^[7]; Jiang, Junke ^[8]; Tao, Shuxia ^[8]; Shen, Qing ^[1]

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+ Show Author Affiliations

1. Univ. of Electro-Communications, Tokyo (Japan)
2. National Renewable Energy Lab. (NREL), Golden, CO (United States); Nankai Univ. (China)
3. National Renewable Energy Lab. (NREL), Golden, CO (United States)
4. Kyushu Inst. of Technology, Kitakyushu (Japan)
5. Ritsumeikan Univ., Shiga (Japan)
6. Miyazaki Univ. (Japan)
7. North China Electric Power Univ., Beijing (China)
8. Eindhoven Univ. of Technology (Netherlands)

Publication Date:

Mon Jan 14 00:00:00 EST 2019

Research Org.:

National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sponsoring Org.:

USDOE National Renewable Energy Laboratory (NREL), Laboratory Directed Research and Development (LDRD) Program

OSTI Identifier:

1513189

Report Number(s):

NREL/JA-5900-71882
Journal ID: ISSN 0897-4756

Grant/Contract Number:  

AC36-08GO28308

Resource Type:

Journal Article: Accepted Manuscript

Journal Name:

Chemistry of Materials

Additional Journal Information:

Journal Volume: 31; Journal Issue: 3; Journal ID: ISSN 0897-4756

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

14 SOLAR ENERGY; 36 MATERIALS SCIENCE; quantum dots; photoluminescence quantum yield; Gel2