Polymeric Electron-Selective Contact for Crystalline Silicon Solar Cells with an Efficiency Exceeding 19%

Wenbo Ji, Thomas Allen, Xinbo Yang, Guosong Zeng, Stefaan De Wolf, Ali Javey

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

Carrier-selective contacts have become a prominent path forward toward efficient crystalline silicon (c-Si) photovoltaics. Among the proposed contacting materials, organic materials may offer simplified and low-cost processing compared with typical vacuum deposition techniques. Here, branched polyethylenimine (b-PEI) is presented as an electron-transport layer (ETL) for c-Si solar cells. The incorporation of a b-PEI interlayer between c-Si(n) and Al leads to a low contact resistivity of 24 mΩ cm2. A silicon heterojunction solar cell integrated with b-PEI is demonstrated achieving a power conversion efficiency of 19.4%, which improves the benchmark efficiency of a c-Si solar cell with an organic ETL. This electron selectivity of b-PEI is attributed to its Lewis basicity, i.e., electron-donating ability, promoting favorable band bending at the c-Si surface for electron transport. Moreover, several other Lewis base polymers perform as efficient ETLs in organic/c-Si hybrid devices, indicating Lewis basicity could be a guideline for future organic ETL design.
Original languageEnglish (US)
Pages (from-to)897-902
Number of pages6
JournalACS Energy Letters
Volume5
Issue number3
DOIs
StatePublished - Feb 19 2020

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors thank Zhen Yuan for help with electrical measurements. Materials characterization was supported by the Electronic Materials Programs, funded by the Director, Office of Science, Office of Basic Energy Sciences, Material Sciences and Engineering Division of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. XPS characterization was performed at the Joint Center for Artificial Photosynthesis, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Device fabrication was funded by King Abdullah University of Science & Technology under Contract No. OSR-2017-GRGG-3383.01.

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