Single-walled carbon nanotubes for heterojunction solar cells

Kehang Cui, Takaaki Chiba, Shohei Chiashi, Esko I. Kauppinen, Shigeo Maruyama*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review


Single-walled carbon nanotubes (SWNTs) with outstanding electronic, optical, mechanical and thermal properties are expected to be the most promising materials for next-generation energy as well as optical and electronic devices. However, the structure-controlled assembling of SWNTs to macroscale for various devices is still challenging. This study focused on the SWNT assemblies for improving the performance of SWNT-Si heterojunction solar cells. A water vapor breath figure method to build up SWNTs into a self-assembled microhoneycomb network for the applications of solar cells has been developed. The micro-honeycomb network consists of vertical aggregated SWNT walls and a buckypaper bottom (quasi two-dimensional random network). The pristine micro-honeycomb structured SWNT-Si heterojunction solar cell shows a record-high fill factor of 72% as well as a stable power conversion efficiency (PCE) of 6.04%. The PCE increased to 10.02% in the dry state after the dilute nitric acid treatment. For comparison, the state-of-the-art randomly oriented SWNT films with high transparency and with low sheet resistance were also used for fabricating solar cells. The PCE and fill factor of the randomly oriented SWNT-Si solar cell are 10.12% and 61%, respectively. In addition, the relationship between the equivalent series resistance and the fill factor was investigated through the diode equation modeling. This study demonstrates that the micro-honeycomb structure formed by the condensation and evaporation of the water vapor is beneficial for improving the performance of solar cell, especially in terms of the fill factor.

Original languageEnglish
Title of host publicationProceedings of the 15th International Heat Transfer Conference, IHTC 2014
Number of pages9
ISBN (Electronic)978-1-56700-421-2
Publication statusPublished - 2014
MoE publication typeA4 Article in a conference publication
EventInternational Heat Transfer Conference - Kyoto, Japan
Duration: 10 Aug 201415 Aug 2014
Conference number: 15


ConferenceInternational Heat Transfer Conference
Abbreviated titleIHTC


  • Carbon nanotubes
  • Nano/Micro
  • Solar energy


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