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Apr 2, 2018 - Silicon (Si)/organic heterojunction solar cells based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and n-type ...
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Buried MoO/Ag Electrode Enables High-Efficiency OrganicSilicon Heterojunction Solar Cells with High Fill Factor Zhouhui Xia, Peng Gao, Teng Sun, Haihua Wu, Yeshu Tan, Tao Song, Shuit-Tong Lee, and Baoquan Sun ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b02403 • Publication Date (Web): 02 Apr 2018 Downloaded from http://pubs.acs.org on April 2, 2018

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ACS Applied Materials & Interfaces

Buried MoOx/Ag Electrode Enables High-Efficiency Organic-Silicon Heterojunction Solar Cells with High Fill Factor Zhouhui Xia, Peng Gao, Teng Sun, Haihua Wu, Yeshu Tan, Tao Song, Shuit-Tong Lee and Baoquan Sun * Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, China KEYWORDS: Anisotropic conductivity; Heterojunction solar cells; Grid design; Optical loss; Tetraethyl orthosilicate

ABSTRACT

Silicon (Si)/organic heterojunction solar cells based on poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) and n-type Si have attracted wide interests because they promise cost-effective and high-efficiency. However, the limited conductivity of PEDOT:PSS leads to an inefficient hole transport efficiency for the heterojunction device. Therefore, a high dense top-contact metal grid electrode is required to assure the efficient charge collection efficiency. Unfortunately, the large metal grid coverage ratio electrode would lead to undesirable

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optical loss. Here, we develop a strategy to balance PEDOT:PSS conductivity and grid optical transmittance via a buried molybdenum oxide/silver grid electrode. In addition, grid electrode coverage ratio is optimized to reduce its light shading effect. The buried electrode dramatically reduces the device series resistance, which leads to a higher fill factor (FF). With the optimized buried electrode, a record FF of 80% is achieved for a flat Si/PEDOT:PSS heterojunction devices. With further enhancement adhesion between PEDOT:PSS film and Si substrate by a chemical cross-linkable silance, a power conversion efficiency (PCE) of 16.3% for organic/textured Si heterojunction devices is achieved. Our results provide a path to overcome the inferior organic semiconductor property to enhance organic-Si heterojunction solar cell.

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ACS Applied Materials & Interfaces

1. INTRODUCTION Organic-silicon (Si) heterojunction solar cells have achieved an impressive power conversion efficiency (PCE) by combining a conducting polymer of poly(3,4-ethylenedioxy-thiophene):poly (styrenesulfonate) (PEDOT:PSS) with crystal n-type Si.1-4 In PEDOT:PSS/Si heterojunction solar cells, incident photons are harvested by Si to generate electron-hole pairs instead of organics. An inversion layer is built in Si when PEDOT:PSS layer is deposited on it. Under electrical field generated in the inversion region of Si, photo-generated charges are swept toward to the corresponding electrodes.5 Here, all the devices are constructed by a simple structure at a relatively low temperature (