Performance Enhancement of Polymer-Free Carbon Nanotube Solar Cells via Transfer Matrix Modeling

Polymer-free (6,5) single-walled carbon nanotubes (SWCNTs) prepared using the gel permeation approach are integrated into SWCNT:C60 solar cells. Evaporation-driven self-assembly is used to form large-area SWCNT thin films from the surfactant-stabilized aqueous suspensions. The thicknesses of various layers within the solar cell are optimized by theoretical modeling using transfer matrix calculations, where the distribution of the electric field within the stack is matched to light absorption by the SWCNTs through either their primary (S11) or secondary (S22) absorption peaks, or a combination thereof. The validity of the model is verified experimentally through a detailed parameter study and then used to develop SWCNT:C60 solar cells with high open-circuit voltage (0.44 V) as well as a cutting-edge internal quantum efficiency of up to 86% through the nanotube S11 transition, over an active area of 0.105 cm2.