posted on 2023-12-21, 14:37authored byKim Anh Huynh, Deuk-Kyu Hwang, Won Jin Choi, Tae Il Lee
The
evolving need for all-weather light detection and ranging (LiDAR)
sensors and cameras for autonomous vehicles, remote sensing surveillance,
and space exploration has spurred the development of transparent heaters.
While LiDAR photon sources have shifted from the visible to the near-infrared
(NIR) range, the use of transparent conductive oxides (TCOs) for heaters
leads to significant optical losses due to their high plasmonic absorption
and reflection in the NIR range. Although different TCO compositions
can be employed to preserve transparency and electrical conductivity
in this range, the choice of dopants, their concentrations, and the
underlying mechanisms remain largely unknown. In this study, we present
TCOs specifically designed for NIR applications with a focus on identifying
new compositions that strike a balance between NIR transparency and
electrical conductivity. We present a 4B–6B transition-metal-doped
indium oxide thin-film heater that exhibits impressive NIR transmittance
(>90%) surpassing that of commonly used indium tin oxide films.
By
incorporating effective dopants such as titanium, hafnium, and tungsten,
we successfully reduced the resistivity and enhanced the electrical
conductivity of indium oxide films. To enhance the practical utility
of the film, we implemented post-treatments comprising argon plasma
treatment and encapsulation with low-molecular-weight poly(dimethylsiloxane),
which resulted in significantly improved performance. The optimized
film exhibited a sheet resistance of 520 Ω/sq and excellent
optical transmittance at 850 nm (89.1%), 905 nm (89.7%), and 1550
nm (92%). Moreover, we successfully integrated defogging and defrosting
capabilities into a commercial LiDAR camera and demonstrated its reliable
operation in challenging environments.