The optical analysis and application of size-controllable Si quantum dots fabricated by multi-hollow discharge plasma chemical vapor deposition

Quantum dot-sensitized solar cells (QDSCs) based on the multiple exciton generation (MEG) of QD are attractive in the field of photochemical cells because the improvement of conventional sensitized solar cells has been stagnant recently. The distinctive characteristics of QDs are their strong photo-response in the visible region and quantum confinement effects. Its theoretical efficiency is much higher than that of solar cell based on the single exciton generation (SEG). Moreover, QDs have tunable optical properties and band-gaps depending on the particle size. But QD materials widely used for QDSC have some disadvantages of toxicity and scarcity. On the other hand, Si as one of good QD materials is abundant and not toxic. Also, Si QD has high stability against light soaking and a high optical absorption coefficient due to quantum size effects. However, the research on Si QD is rare although the quantum effect of Si was already verified. It is one of reasons that the fabrication and collection of Si nano-particles are too difficult. Therefore, this work proposed multi-hollow plasma discharge chemical vapor deposition (CVD). It is possible to collect Si particles unlike conventional CVD and solve the problems of the wet process. The optical properties of Si particles were controlled by varying experimental conditions. In this work, Si particles were fabricated with various sizes and their characteristics were analyzed. Based on the results, Si QD was applied to Si QDSC.