Methods for cis and cigs photovoltaics

Abstract

This invention relates to methods for making materials using a range of compounds, polymeric compounds, and compositions used to prepare semiconductor and optoelectronic materials and devices including thin film and band gap materials for photovoltaic applications including devices and systems for energy conversion and solar cells. In particular, this invention relates to polymeric precursor compounds and precursor materials for preparing photovoltaic layers. This invention further relates to methods for making a CIGS, CIS or CGS material by providing one or more polymeric precursor compounds or inks thereof, providing a substrate, depositing the compounds or inks onto the substrate; and heating the substrate at a temperature of from about 20° C. to about 650° C.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of prior U.S. application Ser. No. 12 / 848,808, filed Aug. 2, 2010, which claims the benefit of U.S. Provisional Application No. 61 / 231,158, filed Aug. 4, 2009, and U.S. Provisional Application No. 61 / 326,540, filed Apr. 21, 2010, each of which is hereby incorporated by reference in its entirety.BACKGROUND[0002]The development of photovoltaic devices such as solar cells is important for providing a renewable source of energy and many other uses. The demand for power is ever-rising as the human population increases. In many geographic areas, solar cells may be the only way to meet the demand for power. The total energy from solar light impinging on the earth for one hour is about 4×1020 joules. It has been estimated that one hour of total solar energy is as much energy as is used worldwide for an entire year. Thus, billions of square meters of efficient solar cell devices will be needed.[0003]Photovoltaic ...

AI Technical Summary

Benefits of technology

[0013]The compounds and compositions of this disclosure are stable and advantageously allow control of the stoichiometry of the atoms in the semiconductors, particularly the metal atoms.

[0016]The polymeric precursor compounds and compositions of this disclosure can provide enhanced processability for solar cell production, and the ability to be processed on a variety of substrates including polymers at relatively low temperatures.

Problems solved by technology

Thus, the usefulness of an optoelectronic or solar cell product is in general limited by the nature and quality of the photovoltaic layers.

In general, CIGS materials are complex, having many possible solid phases.

The difficulties with these approaches include lack of uniformity of the CIGS layers, such as the appearance of different solid phases, imperfections in crystalline particles, voids, cracks, and other defects in the layers.

A significant problem is the inability in general to precisely control the stoichiometric ratios of the metal atoms in the layers.

Without direct control over those stoichiometric ratios, processes to make semiconductor and optoelectronic materials are often less efficient and less successful in achieving desired compositions and properties.

For example, no molecule is currently known that can be used alone, without other compounds, to readily prepare a layer from which CIGS materials of any arbitrary stoichiometry can be made.

A further difficulty is the need to heat the substrate to high temperatures to finish the film.

This can cause unwanted defects due to rapid chemical or physical transformation of the layers.

High temperatures may also limit the nature of the substrate that can be used.

Polymer substrates may not be compatible with the high temperatures needed to process the semiconductor layers.

Moreover, methods for large scale manufacturing of CIGS and related thin film solar cells can be difficult because of the chemical processes involved.

In general, large scale processes for solar cells are unpredictable because of the difficulty in controlling numerous chemical and physical parameters involved in forming an absorber layer of suitable quality on a substrate, as well as forming the other layers required to make an efficient solar cell and provide electrical conductivity.

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