Abstract. Herein, the history of TPV at JX Crystals over the last 15 years is described. Our focus has been on commercial application for TPV components and systems. JX Crystals began as a spin off company when the inventors of the GaSb cell left Boeing with a license to make that cell at JX Crystals. We recosnized that III-V IR sensitive cells such as the GaSb cell were enabling for TPV systems. We began pilot production of GaSb cells in 1994. However, while these cells are necessary for TPV, they are not sufficient by themselves and the development of other system components has been necessary. The development of spectral control and burner and recuperator subsystems will be described here. Unfortunately, a complete TPV system still needs to be fully developed. Various R&D efforts around the world are underway targeting this objective. JX Crystals continues to supply small quantities of cells for these development efforts. Given such a TPV system, cell prices can fall dramatically with volume production.
Keywords: Photovoltaic, Thermophotovoltaics. TPV, GaSb, IR PV cell. PACS: 84.60Jt:
TPV underwent a revival in the early 1990s with the introduction of low bandgap IR sensitive III-V cells. The first of these was the GaSb cell invented in 1989 and then described in 1990 . As shown in figure 1, this cell was first invented as a booster cell for use in high efficiency solar panels. The GaSb cell was made using a simple zinc diffusion process. No epitaxial coatings were required and no toxic gases were used in its fabrication. Subsequently, it was described for use in simple TPV demonstrators such as the one shown in figure 2. The GaSb cell was recognized as key for the development of TPV because it responded out to longer wavelengths than the silicon solar cell thus providing higher power densities in combination with man-made heat sources. This superior performance relative to silicon is highlighted in figure 3.
More complex ternary and quaternary IR cells followed. The reader is referred to a special review issue of Semiconductor Science and Technology  as well as the first 6 conference proceedings in this series for more detailed information on the history7 of TPV through the 1990s.
In this paper, we attempt to focus on commercial applications. This is somewhat problematic since the funding for TPV through the 1990s in the US has been primarily from the US Army and Navy, NASA, and DARPA. In effect, this has meant that the funding relevant here has been primarily from the US Army and DARPA. The work by NASA and the Navy has been directed for applications with nuclear powered IR emitters with lower bandgap cells suited to lower temperature IR emitters. For commercial applications, this funding creates more expensive cells that produce less power. Thus, this funding moves in an opposite direction from the lower cost requirement for commercial TPV systems.