Flexible Solar Cells and Stable High-Efficiency Four-Terminal Solar Cells Using Thin-Film Silicon Technology

Abstract

Amorphous silicon (a-Si:H) materials are used in diverse applications such as in active matrix displays, solar cells etc. These types of devices are constructed as multilayers in a multichamber (or cluster tool) system to avoid cross contamination. In this, each process chamber is separated from others via gate valves leading to optimal performance of an electronic device. The planar substrate, such as glass, is transported via a robotic arm from one chamber to another. We present a new type of system architecture to manufacture electronic devices (thin film silicon transistor and solar cells) on flexible substrates, and propose a reel-to-reel cassette suitable for use in a cluster tool system. We report on the development of flexible thin-film silicon solar cells fabricated on low-cost plastic substrates, which can have major applications in buildings to replace tinted glass. We also report on stable amorphous Si and nano-crystalline Silicon (nc-Si) tandem junction solar cell constructed as a four-terminal (4-T) device, in which the current matching constraint is released from each constituent cell. By merely joining two cells constructed on separate pieces of glass, we have achieved conversion efficiency, > 9%. We show that by constructing the 4-T device on either side of the glass or plastic, > 12% can be achieved. Lastly, we discuss the use of pulsed PECVD technique which should be able to improve the properties of nc-Si material thus providing a road map to > 16% on rigid and flexible substrates.

Inherent paramagnetic defects in layered Si/SiO2 superstructures with Si nanocrystals

“…Neither nanometer-size Si appears to become a direct semiconductor, 2 but was shown to be room-temperature photoluminescent 3 ͑PL͒. 12,13 Two more eye catching applications are the Si-based laser 12,14 and quantum computers, 14 both thought to be achievable with this type of structure. This type of structure is being introduced in everyday life, such as CMOS, where Si NCs are embedded in the gate oxide, 5,6 with applications in FLASH memories, 7 silicon 4 light-emitting diodes that are not yet stable enough for the market requirements, [8][9][10] and usage in photovoltaic applications 11 and solar cells reaching an efficiency over 16%, both on rigid and flexible substrates.…”