Efficient Exciton Relaxation and Charge Generation in Nearly Monochiral (7,5) Carbon Nanotube/C60 Thin-Film Photovoltaics

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• 作者：Dominick J. Bindl ; Michael S. Arnold
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：February 7, 2013
• 年：2013
• 卷：117
• 期：5
• 页码：2390-2395
• 全文大小：337K
• 年卷期：v.117,no.5(February 7, 2013)
• ISSN：1932-7455

文摘

We report on photovoltaic diodes based on bilayer heterojunctions between nearly monochiral, polymer wrapped (7,5) semiconducting carbon nanotube photoabsorbing films and C_60. The internal quantum efficiencies (IQEs) for exciton dissociation and subsequent charge collection at the nanotubes鈥?visible E₂₂ and near-infrared E₁₁ and E₁₁ + X resonances are 84% 卤 7%, 85% 卤 5%, and 84% 卤 14%, respectively. The high IQE at each transition shows that recombination losses during relaxation and/or direct dissociation of 鈥渉ot鈥?E₁₁ + X and E₂₂ excitons are negligible. A peak external quantum efficiency (EQE) of 34% is achieved at the E₁₁ transition. Zero-bias photoresponsivity is invariant up to short-circuit current densities of at least 23 mA cm^鈥?, indicating negligible losses via trion, charge-exciton, and charge鈥揷harge recombination relaxation pathways. An open circuit voltage of 0.49 V and power conversion efficiency of 7.1% are achieved in response to monochromatic excitation of the diodes at the E₁₁ transition. The high IQE across multiple spectral windows, invariant photoresponsivity, and attractive open circuit voltage relative to the 1.18 eV optical bandgap demonstrate the future promise of using monochiral and multichiral semiconducting carbon nanotube films for broadband solar photovoltaic applications.