Temperature-Stable TCO Layer, Method for Production and Application

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The invention describes a temperature-stable transparent conductive oxide (TCO) layer made of doped zinc oxide (ZnO:Al). This TCO layer includes a thin protective layer containing a Group IV element like silicon, which is applied and thermally treated below the critical temperature at which the TCO properties degrade. This protective layer prevents the TCO’s electrical and optical characteristics from deteriorating during subsequent high-temperature processing steps, enabling broader application, especially in thin-film solar cells and coated glasses.

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• Thin-film photovoltaic (solar cell) manufacturing with high-temperature processing
• Production of high-efficiency CIS, CdTe, or poly-Si solar cells requiring TCO contact layers
• Manufacture of technical or commercial glasses with transparent conductive coatings for displays or sensors
• Electronics and optoelectronics requiring transparent electrodes that withstand high post-deposition thermal treatments
• Production of semiconductor devices where thermal stability of transparent conductive electrodes is required

BenefitsContent extracted from patent full text and abstract with AI.

• Enables the use of low-cost, highly transparent, and conductive ZnO:Al layers in high-temperature processes without property degradation
• Expands the processing temperature window above 450°C for devices using TCO layers, improving design options
• Preserves or even improves the electrical and optical properties of the TCO layer after high-temperature processing
• Allows integration of TCOs in advanced photovoltaic cells, potentially increasing solar cell efficiency
• Simplifies manufacturing by decoupling deposition and further processing conditions, potentially reducing costs
• Provides a dual function: thermal protection and, in some cases, a seed (nucleation) layer for subsequent layer growth

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Inventors & Applicants

Patent Abstract

Transparent conductive oxide (TCO) layers of doped zinc oxide (ZnO:Al) are used for example in the thin-film photovoltaic field and are expected to exhibit the highest possible optical transparency and electrical conductivity, which however change significantly as a result of subsequent thermal treatments, thus up until now limiting the use of said TCO layers. The invention therefore provides a TCO layer of doped zinc oxide (ZnO:Al) for integration into layer systems with processing at temperatures in excess of a temperature TP, at which the unprotected TCO layer exhibits changes in the optical and electrical characteristics, comprising a transparent, conductive protective layer (SS) on the surface designated for processing. Said protective layer is created by bringing the TCO layer into contact with a material composition containing at least one element (Si) of the fourth main group of the periodic table and by subsequent heating at a temperature TA lying below the temperature TP, before the TCO layer is subjected to processing at temperatures in excess of the temperature TP. The protective layer (SS) of the invention thus permits a significant expansion of the area of application, in particular thin-film solar cells or commercial glasses with oxide layers (TCO) can now be produced as contact layers or protective layers.