Among various deposition techniques to deposit Cu2ZnSn(S,Se)4 (CZTSSe) thin films, solution-based processes have attracted considerable attention because of their potentially low cost. Most of the reported solution-based methods are based on nonaqueous solvents, such as hydrazine, and organic solvents. We report the deposition of CZTSSe thin films and fabrication of CZTSSe solar cells by a water-based, solution-processed method followed by Se vapor annealing. The effects of Se vapor feeding time on the properties of CZTSSe thin films and the performance of CZTSSe solar cells are investigated. The ratio of Se/(Se+S) can be tuned by changing the Se vapor feeding time. Our results indicate that extending the Se vapor feeding time increases the band gap, slightly increases the lattice constant, and significantly improves the morphologies of the CZTSSe thin films. A remarkable enhancement in the performance was observed from the CZTSSe solar cells annealed with a longer Se vapor feeding time compared with those without Se feeding.
Carbon nanotubes (CNTs) have a potential to be efficient infrared (IR) detection material due to their unique
electronic properties. As a one-dimensional nano-structural material, the ballistic electronic transport property
makes the noise equivalent temperature difference smaller compared with other semi-conducting materials. In
order to verify this unique property, a single pixel CNT-based infrared photodetector is fabricated by depositing
the CNTs on the substrate surface and then aligning them to bridge the electrode gap using the atomic force
microscopy (AFM)-based nano-robotic system. The photon-generated electron-hole pairs within the carbon
nanotube are separated by an external electric field between the two electrodes. The separated carriers contribute
to the current flowing through the carbon nanotube and form the photocurrent. By monitoring the photocurrent,
the incident infrared can be detected and quantified. Experimental results show the good sensitivity of CNTs to
the infrared light.