High speed laser crystallization of particles of photovoltaic solar cells

Abstract

A system and method for enhancing the conversion efficiency of thin film photovoltaics. The thin film structure includes a photovoltaic absorbent layer covered by a confinement layer. A laser beam passes through the confinement layer and hits the photovoltaic absorbent layer. The laser can be pulsed to create localized rapid heating and cooling of the photovoltaic absorbent layer. The confinement layer confines the laser induced plasma plume creating a localized high-pressure condition for the photovoltaic absorbent layer. The laser beam can be scanned across specific regions of the thin film structure. The laser beam can be pulsed as a series of short pulses. The photovoltaic absorbent layer can be made of various materials including copper indium diselenide, gallium arsenide, and cadmium telluride. The photovoltaic absorbent layer can be sandwiched between a substrate and the confinement layer, and a molybdenum layer can be between the substrate and the photovoltaic absorbent layer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is a division patent application of co-pending U.S. patent application Ser. No. 13 / 113,386, filed May 23, 2011.BACKGROUND OF THE INVENTION[0002]The present invention generally relates to material processing methods via high speed laser crystallization, and more particularly to methods for enhancing the conversion efficiency of thin film photovoltaics by increasing crystal size and decreasing the defects of the light absorbent layer.[0003]The conversion efficiency of thin film solar cells depends on the crystallinity of the light absorbent layer (e.g., cadmium telluride (CdTE), copper indium selenide (CIS) and copper indium gallium selenide (CIGS)). Defects such as grain boundary and point defects in current thin film photovoltaics (PVs) degrade the photon-electron conversion efficiency and transportation of electrons. Traditional crystallization techniques used in the photovoltaic (PV) industry, such as Rapid Thermal Annealing (RTA) ...

AI Technical Summary

Benefits of technology

The patent describes a new and improved method for making thin film solar cells using a process called high speed laser crystallization (HSLC). This method allows for larger crystals to be formed, resulting in faster and more efficient solar cells. It also promotes the growth of dense crystals and reduces damage to the part being processed. Compared to conventional techniques, HSLC offers faster production rates, selective processing, energy savings, and the ability to densify packed crystals without complicated temperature control systems. Overall, the HSLC method provides a low-cost and rapid way to make thin film solar cells with better conversion efficiency.

Problems solved by technology

Defects such as grain boundary and point defects in current thin film photovoltaics (PVs) degrade the photon-electron conversion efficiency and transportation of electrons.

Traditional crystallization techniques used in the photovoltaic (PV) industry, such as Rapid Thermal Annealing (RTA) techniques, have several limitations.

These limitations can include issues regarding non-selective heating, slow crystal growth, temperature control for large crystal growth, and the need to use costly vacuum / inert gas environments.

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