Commercial Production of the Group-V Doped Polycrystalline CdTe Source Material for the Next-Generation Photovoltaics

This subtopic intends to support technology transfer from research institutions (universities and national laboratories) to the market. The STTR program is a vehicle to support the creation of new, for-profit entities that will work closely with a research institution. This subtopic solicits applications for spinning out solutions from research institutions with the goal of advancing solar energy technologies by lowering cost, increasing domestic content in solar hardware, and facilitating its secure integration into the nation’s energy grid.
Addressing the Problem: Cadmium Telluride (CdTe) thin film technology has demonstrated its potential as a low-cost, high-performance alternative to Chinese multi-crystalline silicon technology. The primary goal in this effort is to develop a low-cost, high-volume, and scalable CdTe feedstock manufacturing technology for next-generation industrial CdTe photovoltaics (PVs). The CdTe material feedstock will be tuned or optimized for high-efficiency solar cell production used in today’s industrial photovoltaic manufacturing, and the next-generation PV device manufacturing. The success of this effort will move the United States Department of Energy closer to achieving the goals specified in the SunShot initiative by advancing PV performance and reducing manufacturing costs.
Phase 1 Summary: In Phase I, it is proposed to develop the High-Pressure Bridgman (HPB) technique for low-cost and high-volume processing for synthesizing doped and undoped CdTe feedstock into commercial production at RDT. Effort will focus on the technology transfer from Washington State University to RDT. Photovoltaic films will be fabricated and characterized in this effort by the Center for Next Generation Photovoltaics at Colorado State University. A robust CdTe feedstock manufacturing technology and high quality CdTe materials will be available to the solar industry; a process that can be scaled to a production level the industry has not experienced yet. The success of this effort can disrupt the current thin film solar energy supply chain.
Commercial Applications and Other Benefits: CdTe has the physical properties necessary for PV applications; a low-cost manufacturability, and durability. Laboratory CdTe solar cell efficiency has improved from 17% to 21.5%, now matching silicon-based efficiencies. These efficiencies are still well below the CdTe achievable efficiency. At the same time, industrial solar panels have exceeded 18%. The cost of industrial CdTe PVs is now approaching 40¢/W making it the most likely PV technology to reach DOE SunShot goals. The current state-of-the art for CdTe feedstock production is the cold-Traveler Heater Method (Cold-THM) which has limits to the amount of material that can be synthesized within a single run. The HPB method is scalable and capable of producing materials the solar industry is requesting, such as group-V doped CdTe, a material that is very challenging to produce by the cold-THM. From the increased charge size, reduced waste streams, and reduced labor costs associated with the HPB technique, there is a ~43% cost reduction in feedstock CdTe production that can be passed on directly to the customer. There are two primary benefits from the success of this effort through Phase II and beyond: 1) Cost reduction of undoped feedstock CdTe and next-generation CdTe variants, and 2) Paving the pathway to increased CdTe PV performance through group-V doping.