All-carbon nanotube solar cell devices mimic photosynthesis

TL;DR

This paper introduces a bio-inspired solar cell design using semiconducting carbon nanotubes that separates light absorption from power generation, mimicking photosynthesis to improve efficiency.

Contribution

It demonstrates a novel tandem geometry with energy funneling in s-SWCNT diodes, enhancing spectral response without increasing dark current.

Findings

Increased photocurrent magnitude and spectral response.

Effective photon capture across multiple spectral regions.

Maintained low dark leakage with added nanotube layers.

Abstract

Photovoltaics has two main processes: Optical absorption and power conversion. In photosynthesis, the two equivalent processes are optical absorption and chemical conversion. Whereas in the latter, the two processes are carried out by distinct proteins, in conventional photovoltaic diodes, the two processes are convoluted because the optical and transport paths are the same, leading to inefficiencies. Here, we separate the site and direction of light absorption from those of power generation to show that semiconducting single-walled carbon nanotubes (s-SWCNTs) provide an artificial system that models photosynthesis in a tandem geometry. Using different s-SWCNT chiralities, we implement an energy funnel in dual-gated p-n diodes. This enables the capture of photons from multiple regions of the solar spectrum and the funneling of photogenerated excitons to the smallest bandgap s-SWCNT layer, where they become free carriers. As a result, we demonstrate an increase in the magnitude and spectral response of photocurrent by adding more s-SWCNT layers of different bandgaps without a corresponding deleterious increase in the dark leakage current.