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Molecular Multilayer Organic Solar Cells with Large Excitonic Diffusion Length

  • Seunghyup Yoo (a1), William J Potscavage (a2), Benoit Domercq (a3), Sung-Ho Han (a4), Dean Levi (a5) and Bernard Kippelen (a6)...


We report on the photovoltaic properties of organic solar cells based on pentacene and C60 thin films. A peak external quantum efficiency (EQE) of 69 % at a wavelength of λ = 668 nm is achieved upon optimization of the exciton blocking layer (EBL) thickness. Complex optical functions of pentacene films are measured as a function of wavelength by spectroscopic ellipsometry and used to analyze the EQE spectra. Detailed analysis of the EQE spectra indicate that the pentacene layers exhibit large excitonic diffusion lengths of ∼70 nm and that the performance improvement in EQE can be attributed to the influence of the thickness of the EBL layer on the carrier collection efficiency.



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