Self-Assembled Microhoneycomb Network of Single-Walled\nCarbon Nanotubes for Solar Cells

Abstract

We\npropose a water vapor treatment to direct the formation of single-walled\ncarbon nanotubes (SWNTs) into a self-assembled microhoneycomb network\n(μ-HN) for the application to SWNT-Si solar cells. The μ-HN\nconsists of vertical aggregated SWNT walls and a buckypaper bottom.\nThis hierarchical structure exhibits lower sheet resistance and higher\noptical transmittance compared with buckypaper. The pristine μ-HN\nSWNT-Si solar cell shows a record-high fill factor of 72% as well\nas a power conversion efficiency (PCE) of 6% without optimizing the\ndiameter or height of the vertically aligned SWNTs. The PCE remains\nstable for weeks under ambient condition, and a PCE exceeding 10%\nis achieved in the dry state after dilute nitric acid treatment.