Front electrode for use in photovoltaic device and method of making same
This invention relates to a front electrode/contact for use in an electronic device such as a photovoltaic device. In certain example embodiments, the front electrode of a photovoltaic device or the like includes a multilayer coating including at least one transparent conductive oxide (TCO) layer (e.g., of or including a material such as tin oxide, ITO, zinc oxide, or the like) and/or at least one conductive substantially metallic IR reflecting layer (e.g., based on silver, gold, or the like). In certain example instances, the multilayer front electrode coating may include one or more conductive metal(s) oxide layer(s) and one or more conductive substantially metallic IR reflecting layer(s) in order to provide for reduced visible light reflection, increased conductivity, cheaper manufacturability, and/or increased infrared (IR) reflection capability. In certain example embodiments, the front electrode acts as not only a transparent conductive front contact/electrode but also a short pass filter that allows an increased amount of photons having high energy (such as in visible and near infra-red regions of the spectrum) into the active region or absorber of the photovoltaic device.
1 - 13 . (canceled)
14 . A front electrode structure for a photovoltaic device, the front electrode structure comprising:
a front substantially transparent glass substrate;
a first layer comprising one or more of silicon nitride, silicon oxide, silicon oxynitride, and/or tin oxide;
a second layer comprising metal oxide and having a higher refractive index (n) than the first layer, wherein at least the first layer is located between the front substrate and the second layer;
a third layer comprising metal oxide;
a fourth layer that is conductive and comprises silver, wherein at least the third layer is provided between the conductive layer comprising silver and the second layer;
a fifth layer that is a transparent conductive oxide (TCO) layer comprising metal oxide between the conductive layer comprising silver and a sixth layer that is a transparent conductive oxide (TCO) layer comprising metal oxide;
wherein the fifth layer has a thickness substantially greater than that of the sixth layer, and
wherein a layer stack comprising said first, second, third, fourth, fifth and sixth layers is provided on an interior surface of the front glass substrate facing the semiconductor film of the photovoltaic device.
15 . The front electrode structure for a photovoltaic device of claim 14 , wherein an exterior surface of the glass substrate is etched, but the interior surface of the glass substrate on which the layer stack is provided is not etched and is substantially flat.
16 . The front electrode structure for a photovoltaic device of claim 14 , wherein the front electrode structure acts not only as a front electrode for the photovoltaic device, but also as a short pass filter that (i) allows a large amount of photons having energy in the visible and near-IR regions into the semiconductor film, and (ii) blocks significant amounts of other IR radiation from reaching the semiconductor film.
17 . The front electrode structure for a photovoltaic device of claim 14 , wherein the semiconductor film comprises a-Si, and the front electrode structure has a transmission of at least 85% in at least a majority of a range of from 450-700 nm.
18 . The front electrode structure for a photovoltaic device of claim 14 , wherein the semiconductor film comprises a-Si, and the front electrode structure has a transmission of at least 87% in at least part of a range of from 450-700 nm.
19 . The front electrode structure for a photovoltaic device of claim 14 , wherein the semiconductor film comprises CdS and/or CdTe, and the front electrode structure has a transmission of at least 90% in at least a majority of a range of from 500-600 nm
20 . The front electrode structure for a photovoltaic device of claim 14 , wherein the semiconductor film comprises CdS and/or CdTe, and the front electrode structure has a transmission of at least 92% in at least part of a range of from 500-600 nm.
21 . The front electrode structure for a photovoltaic device of claim 14 , wherein the front substrate and all layers of the photovoltaic device on a front side of the semiconductor film taken together have an IR reflectance of at least about 45% in at least a substantial part of an IR wavelength range of from about 1400-2300 nm.
22 . A photovoltaic device including the front electrode structure of claim 14 .