Technical Proceedings of the 2012 Clean Technology Conference and Trade Show

Cleantech 2012

Chapter 2: Renewable Energy Technologies

G.J. Cheng, Yi Zhang
Purdue University, US
78 - 81
direct pulsed laser crystallization, thin film solar cell, photoactive thin films, CIGS
Photoactive semiconductor materials used for thin film solar cells have been considered one of the most promising technologies with demonstrated high efficiency in both lab scale cells. World-wide research and development (R&D) have been carried out for years to improve the quality of thin film solar cells, especially on the absorbent layer. The most often seen obstacles are defects in the absorbent layer. Rapid thermal annealing (RTA) has been widely used to reduce internal defects because of its relatively low cost and uniform crystallization. However, RTA has some intrinsic problems, including non-selective, slow, high temperature, quasi-static temperature change leading to poor control of grain size, use of costly vacuum/inert gas systems. Here, a cost effective and rapid thermal processing technique called direct pulsed laser crystallization (DPLC) is introduced to crystallize photoactive nanoparticle ink for thin film solar cells at room temperature and atmospheric pressure. DPLC has great potentials in scalable production because it is performed at atmospheric environment and completed within a few hundreds of nanoseconds. A typical increase of 7.9% (visible range) and 19.2% (near infrared range) in optical absorptance is obtained under optimal DPLC conditions. Selectivity and smoothening effect of DPLC are also discussed in this study.
Direct Pulsed Laser Crystallization of Photoactive thin films at Room Temperature