II-1. Bifacial CIGS Thin-film Solar Cell and Transparent Solar Module

In the past decades, rapid constructions of civilization have yielded worldwide reduction of the planted area that could harvest solar energy by photosynthesis. To meet the significant energy demands from the populated area, a new type of photovoltaic system is necessary. In this project, we aim to develop a transparent CIGS PV module that can be utilized for building-integrated PV (BIPV) or bi-facial PV system. CIGS offers unique properties over silicon such as thin film processibility with high quantum efficiencies, being an ideal candidate for transparent PV applications. Particularly, we design a novel scheme for making opaque CIGS module more transparent without sacrificing the photo-voltage as well as the fill factor. Understanding CIGS growth on a transparent electrode and hence engineering the interface will be of significant importance in this project. 

II-2. Flexible CIGS thin-film PV Module

Conventional CIGS fabrication process requires a high temperature (>550 ℃) for sufficient crystallization, rendering fabrication of a CIGS solar cell on a plastic substrate very challenging. In this project, we aim to understand the physics behind the CIGS crystal growth at low temperatures and build a strategy to stack functional CIGS films on a plastic substrate. Our goal is to demonstrate a high efficiency flexible CIGS module by simple co-evaporation process, potentially allowing roll-to-roll fabrication of CIGS PV module. The project consists of three parts:

1) Engineering research for mechanically stable bottom electrode(Mo)/plastic substrate

2) Development of a low temperature(<450 ℃), high performance CIGS co-evaporation process

3) Monolithic integration of CIGS modules on a plastic substrate by all-laser scribing process

II-3. Ultrafast Laser Process for Lithography and Material Engineering 

We explore the potential for all-laser scribing process to make monolithically integrated PV modules. Most of thin film module scribing techniques has relied on mechanical scribing which yielded a significant dead-area over the entire module surface. With our high resolution laser scribing technology (ns or ps pulse lasers), we could monolithically integrate CIGS modules with the least sacrifice of the dead zone. We expand the technology to diverse PV systems such as transparent, flexible, tandem, or bi-facial PV modules.