Toward efficient carbon nanotube/P3HT solar cells: active layer morphology, electrical, and optical properties

Publication Type:

Journal Article

Source:

Nano Lett., ACS Publications, Volume 11, Issue 12, p.5316-5321 (2011)

ISBN:

1530-6984

Keywords:

2011, 2013 and earlier

Abstract:

We demonstrate single-walled carbon nanotube (SWCNT)/P3HT polymer bulk heterojunction solar cells with an AM1.5 efficiency of 0.72%,
significantly higher than previously reported (0.05%). A key step in
achieving high efficiency is the utilization of semiconducting SWCNTs
coated with an ordered P3HT layer to enhance the charge separation and
transport in the device active layer. Electrical characteristics of
devices with SWCNT concentrations up to 40 wt % were measured and are
shown to be strongly dependent on the SWCNT loading. A maximum open
circuit voltage was measured for SWCNT concentration of 3 wt % with a
value of 1.04 V, higher than expected based on the interface band
alignment. Modeling of the open-circuit voltage suggests that despite the
large carrier mobility in SWCNTs device power conversion efficiency is
governed by carrier recombination. Optical characterization shows that
only SWCNT with diameter of 1.3-1.4 nm can contribute to the photocurrent
with internal quantum efficiency up to 26%. Our results advance the
fundamental understanding and improve the design of efficient
polymer/SWCNTs solar cells.