Electron-selective quinhydrone passivated back contact for high-efficiency silicon/organic heterojunction solar cells

• Published in: Solar energy materials and solar cells Vol. 185; pp. 218 - 225
• Main Authors: Zou, Ziyu, Liu, Weiqing, Wang, Dan, Liu, Zhaolang, Jiang, Ershuai, Wu, Sudong, Zhu, Juye, Guo, Wei, Sheng, Jiang, Ye, Jichun
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2018; Elsevier BV
• Subjects: Aluminum; Capacitance; Carrier lifetime; Carrier transport; Contact resistance; Dark current; Dipoles; Electric contacts; Electrical measurement; Electron-selective passivated rear contact; Energy conversion efficiency; Grafting; Heterojunctions; Interface dipole; Interfacial engineering; Interfacial properties; Low temperature; Minority carriers; Open circuit voltage; Organic chemistry; Photovoltaic cells; Quinhydrone surface modification; Si/PEDOT:PSS heterojunction solar cells; Silicon; Solar cells; Solar energy; Voltage; Wettability; Interface dipole; Quinhydrone surface modification; Si/PEDOT:PSS heterojunction solar cells; Electron-selective passivated rear contact; Interfacial engineering
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2018.05.041

Interfacial properties play a critical role in the dynamic process of carrier transport in dopant-free silicon (Si) heterojunction solar cells (HSCs), based on the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). In this study, we use quinhydrone (QHY) to engineer the interfacial properties by grafting the semiquinone (QH) on Si surface at low temperature. The QH monolayer provides effective chemical and field-effect passivation by the surface dangling-bond saturation and its interface dipole, respectively, and results in a large minority carrier lifetime of 477 μs. At the front Si/PEDOT:PSS interface, the QH-terminated Si surface presents higher wettability for the improved contact at the Si/PEDOT:PSS junction. At the rear Al/Si interface, the work function of Al film is reduced significantly to form ohmic contact for electron-selective transport. The dark current-voltage and capacitance-voltage measurements show the improved electric characteristics with a higher carrier collection efficiency. Furthermore, the silicon band bending generated by the QH dipoles enhances the overall built-in potential of Si/PEDOT:PSS HSCs for a larger open-circuit voltage. As a result, the QHY modified Si/PEDOT:PSS HSC yields a power conversion efficiency of 13.29%. This approach demonstrates that the organic grafting is a simple, effective and low-cost method for the interface engineering to achieve high-efficiency HSCs. Quinhydrone is used to engineer the interfacial properties in Si/PEDOT:PSS heterojunction solar cells, received high power conversion efficiency of 13.29% based on electron-selective passivated back contact and good heterojunction contact. [Display omitted] •Electron-selective quinhydrone passivated back contact.•Efficiently passivated by chemical bonding and field-effect of interfacial dipole.•Interfacial engineering for the improved junction contact and carrier collection.•Reversing silicon band bending for a remarkable open-circuit voltage of 635 mV.•13.29% power conversion efficiency of Si/PEDOT:PSS heterojunction solar cell.