Scalable and Solid‐State Redox Functionalization of Transparent Single‐Walled Carbon Nanotube Films for Highly Efficient and Stable Solar Cells
2017; Wiley; Volume: 7; Issue: 18 Linguagem: Inglês
10.1002/aenm.201700449
ISSN1614-6840
AutoresKehang Cui, Qian Yang, Il Jeon, Anton S. Anisimov, Yutaka Matsuo, Esko I. Kauppinen, Shigeo Maruyama,
Tópico(s)Organic Electronics and Photovoltaics
ResumoThis study reports a scalable and room‐temperature solid‐state redox functionalization process for single‐walled carbon nanotubes (SWNTs) with instant efficacy and high stability. By drop‐casting/spin‐coating CuCl 2 /Cu(OH) 2 colloidal ethanol solution onto SWNT films, the sheet resistance of the SWNT films achieves 69.4 Ω sq −1 at 90% transparency without noticeable increase for more than 12 months. The charge transfer mechanism between the redox and the SWNTs is revealed by Raman and X‐ray photoelectron spectroscopies. The SWNT/silicon solar cells are utilized as a benchmark to evaluate the effectiveness of the redox functionalization process and its compatibility for device integration. The power conversion efficiency of the SWNT/Si solar cell increases by 115% after redox functionalization, reaching the value of 14.09% without degradation in the ambient for over 12 months. Temperature‐dependent operation characteristics of the redox functionalized SWNT/Si solar cells demonstrate that the Fermi level unpinning and enhanced tunneling of the charge carriers contribute to the significant improvement of the photovoltage and fill factor. The CuCl 2 /Cu(OH) 2 redox also serves as an antireflection layer, resulting in a 20% increase of the photocurrent. The proposed redox functionalized SWNTs are promising as multifunctional transparent conductive films for wide‐range solar cell applications.
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