Nanoengineered CIGS Thin Films for Low Cost Photovoltaics

摘要

Low cost manufacturing of Cu(In,Ga)Se_2(CIGS) films for high efficiency photovoltaic devices by the innovativeField-Assisted Simultaneous Synthesis and Transfer (FASST) process is reported. The FASST process is a two-stagereactive transfer printing method relying on chemical reaction between two separate precursor films to form CIGS, onedeposited on the substrate and the other on a printing plate in the first stage. In the second stage these precursors are broughtinto intimate contact and rapidly reacted under pressure in the presence of an applied electrostatic field. The methodutilizes physical mechanisms characteristic of anodic wafer bonding and rapid thermal annealing, effectively creating asealed micro-reactor that ensures high material utilization efficiency, direct control of reaction pressure, and low thermalbudget. The use of two independent ink-based or PVD-based nanoengineered precursor thin films provides the benefits ofindependent composition and flexible deposition technique optimization, and eliminates pre-reaction prior to the secondstage FASST synthesis of CIGS. High quality CIGS with large grains on the order of several microns are formed in justseveral minutes based on compositional and structural analysis by XRF, SIMS, SEM and XRD. Cell efficiencies of 12.2%have been achieved using this method.