The synthesis and application of chalcogenide materials has widely been investigated as solar cell materials over the past decades due to their semiconducting properties that can be tailored by the careful manipulation of synthetic conditions. In particular, Cu(In,Ga)Se2 (CIGS) or CuInSe2 (CIS) are one of the most promising materials as light absorbers in the area of solar cell research and production. Recently, the CIGS (or CIS) solar cell process using nanoparticles with solution-based approach has been spotlighted instead of traditional vacuum based process.
Thus far, most CIGS (or CIS) thin film coating methods with nanoparticles have used CIGS (or CIS) nanoparticles and organic binders. These are relatively easy to remove excess organics through the pores between the particles, and thus the particles can be purely synthesized. However, it is intricate to make quaternary (or ternary) nanoparticles, and has some difficulties to remove pores in order to obtain smooth layers after the final heat treatment (selenization). To achieve improved results in this report, the hybrid inks using binary nanoparticles and ion-dissolved precursor solutions were introduced for reducing pores and the step of nanoparticle synthesis.
In Chapter 1, general introduction about CIGS solar cell and non-vacuum process approached by nanoparticles was established.
In Chapter 2 as the first step of introducing concepts for the hybrid ink, binary copper selenide (Cu-Se) nanoparticles were synthesized by the low temperature colloidal method. Initially, the Cu-Se nanoparticles was expected to play a role of a flux to generate smooth layers with other chalcogenide nanoparticles (such as In-Se and Ga-Se) yielding CIGS thin layers because the eutectic point of Cu-Se is relatively low (around 523 oC) compared to those of In-Se and Ga-Se, according to the phase diagram. However, even though the Cu-Se layer was obtained, the layer surface was rough and the condition with the Cu-Se nanoparticl...