The intrinsic SnO2/ITO-soda-lime glass substrate
used here has a relatively low transmittance and hence
negatively impacts the photocurrent. Nevertheless,
nanotube solar cells exhibit a relatively high short
current density of 25.5 mA/cm2 under 1-sun illumination
without any antireflective coating. The high Jsc depends
on effective light absorption, as well as efficient
carrier generation and collection.