Keywords

Photovoltaics, Compact Model, Solar Cells, Photoluminescence, Nanotechnology

Presentation Type

Poster

Research Abstract

A grand challenge of photovoltaics (PV) is to find materials offering a promising combination of low costs and high efficiencies. While III-V material-based PV cells have set many world records, often their cost is much greater than other commercial cells. To help address this gap, thin-film vapor-liquid-solid (TF-VLS) grown Indium Phosphide (InP) PV cells have recently been developed, which both eliminate a key source of high costs and offer a direct bandgap of 1.34eV with potential to approach maximum theoretical efficiencies. However, the unanticipated phenomenon of open circuit voltage (Voc) degradation has prevented TF-VLS grown InP PV cells from achieving their theoretical efficiencies, which appears to be caused by effective bandgap narrowing in certain portions of the cells. To address this issue, we have developed a 3D model for these PV cells in Xyce, a SPICE-like free circuit modeling software. Our model quantifies lateral variation of TF-VLS grown cells observed in photoluminescence (PL) images with two sets of unit cell parameters. It turns out that the PL intensity correlates to PV cells of different bandgaps (Eg). Based on user-defined cutoffs, we are able to categorize the expected bandgap and reduced bandgap cells. With the addition of an appropriate shunt resistance, it is possible to explain most of current-voltage relationship with this model. Finally, we are building a web-enabled tool to allow users to upload their own heterogeneous PV cell data into our model, using a graphical user interface on nanoHUB.org, an open-access science gateway for cloud-based simulation tools and resources for research and education in nanoscale science and technology.

Session Track

Energy

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Aug 4th, 12:00 AM

Performance of TF-VLS Grown InP Photovoltaic Cells

A grand challenge of photovoltaics (PV) is to find materials offering a promising combination of low costs and high efficiencies. While III-V material-based PV cells have set many world records, often their cost is much greater than other commercial cells. To help address this gap, thin-film vapor-liquid-solid (TF-VLS) grown Indium Phosphide (InP) PV cells have recently been developed, which both eliminate a key source of high costs and offer a direct bandgap of 1.34eV with potential to approach maximum theoretical efficiencies. However, the unanticipated phenomenon of open circuit voltage (Voc) degradation has prevented TF-VLS grown InP PV cells from achieving their theoretical efficiencies, which appears to be caused by effective bandgap narrowing in certain portions of the cells. To address this issue, we have developed a 3D model for these PV cells in Xyce, a SPICE-like free circuit modeling software. Our model quantifies lateral variation of TF-VLS grown cells observed in photoluminescence (PL) images with two sets of unit cell parameters. It turns out that the PL intensity correlates to PV cells of different bandgaps (Eg). Based on user-defined cutoffs, we are able to categorize the expected bandgap and reduced bandgap cells. With the addition of an appropriate shunt resistance, it is possible to explain most of current-voltage relationship with this model. Finally, we are building a web-enabled tool to allow users to upload their own heterogeneous PV cell data into our model, using a graphical user interface on nanoHUB.org, an open-access science gateway for cloud-based simulation tools and resources for research and education in nanoscale science and technology.