We believe that the primary market opportunity in the thermoelectric space is the breakthrough development of a high performance material that can be manufactured using low cost bulk methods. A commercial device must target efficiencies of 15% plus, and a cost below $5 per watt to unlock the rapid growth potential in various markets. None of the spectacular gains in thermoelectric performance regularly reported at universities or research institutes have been transferred into the marketplace, largely because they are based upon approaches that are too intricate and expensive for the commercial world.
The reason why MicroPower’s technology is such an important breakthrough is that it can deliver high efficiency at low cost, and in a temperature range of 250°C – 600°C that opens up opportunities not served by the current materials. Can we say with 100% certainty that no other company can make the same claim? No, but what we can say is that all of our current partners and customers (including two US Government labs, both experts in the field) tell us that no-one else has delivered prototype devices that come close to matching MicroPower’s products in terms of performance, durability and commercial viability.
Below is an explanation of how we have developed this competitive edge in an increasingly popular marketplace.
Highly efficient base material
Our base material has always needed to possess different qualities to standard thermoelectric material for it to be suitable for our patented barrier layer (see below). Combining mechanical stability, barrier compatibility and solid starting efficiency required extensive testing and analysis in conjunction with a world leader in this field, and during this process we realised that that is was indeed possible to obtain the characteristics we required, and significantly enhance the base material efficiency. We then brought this expertise and equipment in-house, providing us with a world class base material production capability on-site.
A key factor in our ability to produce highly efficient chips is what we call the “barrier layer”. By depositing atoms in certain concentrations and in certain geometries, we can significantly enhance the efficiency of any semiconductor material that exhibits an easy change of conductivity through doping. To do this, we use a molecular beam epitaxy tool which, once considered too expensive for commercial production, can carry this out cost-effectively. In addition, the ability to augment the performance of alternative thermoelectric materials mitigates the risk of operating in only two material systems.
High temperature interconnects
Applying metal plates to chips to enable them to be electrically connected in a module, without losing efficiency, sounds like a straightforward engineering task. However, while this issue has been, to a large extent, overcome in BiTe modules (<250°C), it soon became clear to us that there was no such solution for higher temperature operation. Consequently, we entered into an R&D agreement with the US Army Research Lab to develop mechanically stable, high temperature compatible interconnect structures for our material, and novel plating techniques were subsequently developed to apply these metal structures to our chips.
From MicroPower’s beginnings, the plan had always been to produce chips and outsource module manufacturing to an existing firm. However, to put it simply, no-one knew how to make commercial high-temperature modules because it had never been done before. Consequently, while there has been some minor support from outside, MicroPower has effectively had to develop this module production capability itself. While the obvious drawback has been the time it has taken, we now have our own bespoke module manufacturing capability which provides us with greater knowledge and control moving forward.