Associate Professor Xie Liqiang & Professor Wei Zhanhua of Huaqiao University, Dr. Jinyan Zhang of Goldstone Energy AM: High-efficiency and stable perovskite/silicon tandem solar cells are realized by using an indium-tin oxide interlayer with adjustable contact resistance
【Article Information】
An indium-tin oxide interlayer with adjustable contact resistance is used to achieve efficient and stable perovskite/silicon tandem solar cells
First Author: Jin Yongbin, Hui Ping, Fang Zheng
Corresponding Authors:XIE Li-qiang*,ZHANG Jin-yan*,WEI Zhan-hua*
Unit: Huaqiao University, Goldstone Energy (Fujian) Co., Ltd
【Background】
Tandem solar cells have attracted a lot of attention because of their potential to break through the conversion efficiency limit of the Shockley-Quayser theory of single-junction solar cells. Perovskite/silicon tandem solar cells are an emerging technology that combines the excellent photoelectric properties of perovskites with the performance of mainstream industrial silicon-based solar cells. As a result, the rapid progress of perovskite/silicon tandem solar cells in recent years has led to impressive conversion efficiency. However, the imperfect charge behavior at the perovskite/electron transport layer (ETL)/transparent conductive oxide (TCO) interface limits the performance of perovskite/silicon tandem solar cells. TCOs such as indium tin oxide (ITO) and indium zinc oxide (IZO) are typically prepared by sputtering.
Due to the high-energy sputtering particles, the direct deposition of TCO on fullerene (C60) ETL may cause severe sputtering damage to the ETL and perovskite layers. Therefore, a protective layer is required to guarantee a high interface quality. In addition, imperfect charge behavior due to energy level mismatch, carrier recombination, and high contact resistance at the ETL/TCO interface leads to significant energy losses from photogenerated carriers. Therefore, in order to minimize interfacial energy loss and avoid sputtering damage, it is essential to construct a semiconductor interlayer with energy level matching and tunable contact resistance at the ETL/TCO interface.
【Introduction】
Recently, the team of Associate Professor Xie Liqiang and Professor Wei Zhanhua from Huaqiao University and the team of Dr. Jinyan Zhang of Goldstone Energy published a paper entitled "Efficient and Stable Monolithic Perovskite/Silicon Tandem Solar Cells Enabled by ContactResistance-Tunable" in the internationally renowned journal Advanced Materials Indium Tin Oxide Interlayer". In this opinion paper, the contact resistance with the transparent conductive electrode (TCO) was effectively adjusted by electron beam evaporation (EBE) with an adjustable indium tin oxide interlayer, and the interfacial contact was optimized, and finally the certified conversion efficiency of 30.3% was achieved on a 1 cm2 perovskite/silicon tandem solar cell. This new interfacial layer has great potential in perovskite/silicon tandem solar cells and other perovskite-based tandem cells, and also marks a big step forward for perovskite/silicon tandem solar cells to practical commercial applications.
Figure 1. Sn-doped In2O3 films were prepared and characterized by electron beam evaporation.
Figure 2. The energy level arrangement between In2O3 and IZO with different Sn contents.
Figure 3. Performance characterization of the corresponding translucent perovskite solar cells.
Figure 4. Performance and light operation stability of the corresponding perovskite/silicon tandem solar cells.
【Main points of the text】
Point 1: Regulation of the contact resistance between the indium tin oxide interlayer and the transparent electrode IZO
The contact resistance is closely related to the transport of carriers at the interface, and in order to measure the contact resistance between the deposited tinned indium oxide film and the IZO, the transfer length method (TLM) is used, which is a technique commonly used in silicon-based solar cells to measure the contact resistance between a metal electrode and an adjacent semiconductor layer. It is worth noting that when the Sn doping content is less than 8%, the contact resistance gradually decreases with the increase of Sn doping content. However, when the Sn doping content is 12%, the contact resistance increases significantly due to overdoping. Therefore, when the doping content of Sn reaches 8%, the contact resistance with IZO is the smallest, and the interface contact is effectively improved.
Point 2: The band structure relationship between the indium tin oxide middle layer and the transparent electrode IZO
The increase of the doped Sn content leads to a continuous decrease in the conduction band nadir (CBM) and Fermi level (EF) of the corresponding intermediate layer, which can be attributed to the enhancement of the degree of oxidation after doping. It is worth noting that when the Sn content reaches 8%, the band structure of the corresponding intermediate layer has the best compatibility with IZO, resulting in minimal energy loss. Conversely, at 12% Sn, both CBM and EF were lower than IZO, hindering electron transport. At the same time, the atomic probe microscopy (AFM) and Kelvin probe microscopy (KPFM) were characterized by atomic probe microscopy (AFM) and Kelvin probe microscopy (KPFM), and it was found that the potential of the middle shell was higher than that of IZO when the Sn doping content was 0%. With the increase of Sn content, the potential of the mesolayer decreases gradually. When the Sn doping reaches 8%, the middle layer and IZO have the same potential, showing a uniform distribution pattern. When the Sn doping amount reaches 12%, the potential of the mesolayer is lower than that of IZO. These observations are consistent with the previously discussed band structure, i.e., In2O3 incorporated with 8% Sn achieves optimal energy level alignment with IZO.
Point 3: The performance relationship between the indium-tin oxide interlayer and the corresponding perovskite translucent devices and perovskite/silicon tandem solar cells
The performance of translucent perovskite solar cells shows that increasing the Sn doping content will improve the conversion efficiency at first, but then gradually decrease. Among them, the 8% Sn-doped In2O3 can significantly increase the open-circuit voltage and fill factor of the corresponding translucent device, thereby increasing the conversion efficiency to 20.7%. This improvement is attributed to the excellent electrical properties of the 8% Sn-doped In2O3 itself and its good contact with IZO, which reduces the energy loss between the two. The same perovskite/silicon tandem solar cells achieved a conversion efficiency of 30.8% (30.3% efficiency certified by a third party), and the corresponding packaged device maintained 98% of the initial efficiency after 1078 hours of continuous light operation.
【Article Link】
Efficient and Stable Monolithic Perovskite/Silicon Tandem Solar Cells Enabled by Contact-Resistance-Tunable Indium Tin Oxide Interlayer
https://onlinelibrary.wiley.com/doi/10.1002/adma.202404010
【About the Corresponding Author】
谢立强副教授简介：谢立强，福建省杰青。 现为华侨大学材料科学与工程学院及发光材料与信息显示研究院副教授，硕士生导师。 2017年毕业博士于厦门大学化学系，师从毛秉伟教授和田中群院士。 目前的研究方向为钙钛矿太阳能电池和钙钛矿/硅叠层太阳能电池，已经以第一作者或通讯作者在Nature Communications(2), Journal of the American Chemical Society(2), Advanced Materials(3), Advanced Energy Materials(2)等重要期刊发表研究论文30余篇。
Dr. Jinyan Zhang's Profile: Jinyan Zhang, Ph.D. in Materials Science, Kanazawa University, Japan, is currently the general manager of the R&D Department of Goldstone Energy. Expert in semiconductor equipment and solar energy technology, one of the pioneers of high-performance silicon-based solar cells and low-cost and high-efficiency solar cells in the world. He led the integration of Kingstone Energy's advanced technology and committed to the research and development of heterojunction 1.5 generation products. He has been engaged in industrial technology research and development, process development and system integration in the semiconductor and photovoltaic fields for nearly 30 years. He has published 66 professional academic papers in top international academic journals. Obtained 15 invention patents.
Professor Wei Zhanhua is a professor and doctoral supervisor of the Institute of Luminescent Materials and Information Display, School of Materials Science and Engineering, Huaqiao University, Dean of the Institute of Luminescent Materials and Information Display, and Vice Dean of the School of Materials Science and Engineering. In July 2011, he graduated from the Department of Chemistry of Xiamen University with a bachelor's degree. In August 2015, he graduated from the Department of Chemistry of the Hong Kong University of Science and Technology with a Ph.D. degree. From September 2015 to April 2016, he was engaged in postdoctoral research at the School of Physical and Mathematical Sciences (SPMS) at Nanyang Technological University, Singapore.
In May 2016, he joined the School of Materials Science and Engineering of Huaqiao University, and founded the Institute of Luminescent Materials and Information Display in December 2019 He has published more than 100 research papers in high-level journals such as Materials. He has presided over the national key R&D program projects and regional joint key projects, and won awards such as the first prize of Fujian Natural Science Award in 2022 and the Youth Chemistry Award of the Chinese Chemical Society in 2021.
【Group Introduction】
In December 2019, the Institute of Luminescent Materials and Information Display of Huaqiao University was established. At present, relying on the School of Materials Science and Engineering, the institute has two first-level discipline doctoral programs in materials science and engineering and chemistry, and a key laboratory of optoelectronic materials and advanced manufacturing in Xiamen. At present, the dean of the institute is Professor Wei Zhanhua, a national high-level young talent, with 10 full-time teachers, 2 postdoctoral researchers, 3 administrative staff, and more than 40 master's and doctoral students (including joint training from other universities).
The main research directions of the institute are: (1) luminescent materials and devices; (2) Solar cell materials and devices; (3) Design and preparation of photovoltaic functional materials; (4) flexible optoelectronic materials and devices; (5) Other optoelectronic materials and devices; (6) Optophysics and Device Physics.
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