Consortium Seeks to Advance Tandem Perovskite-Silicon Solar Cells

A public-private consortium funded by the U.S. Department of Energy (DOE) aims to overcome key challenges in bringing halide perovskite materials to the solar cell market. 

 

A perovskite solar cell. Image used courtesy of National Renewable Energy Laboratory

 

The three-year Tandems for Efficient and Advanced Modules using Ultrastable Perovskites (TEAMUP) partnership will launch this fall to research various stability and durability improvements to boost the efficiency and lifetime of tandem perovskite solar cells. 

The current industry-standard semiconductor component in modern solar panels is silicon, which provides a high level of performance but comes with heavier energy requirements and production costs. As in silicon-based solar cells, halide perovskites can also serve as a semiconductor, absorbing energy from sunlight and producing an electrical current via electrons. It’s an emerging competitor offering promising efficiency and more attractive economic benefits than its silicon counterpart. 

Tandem perovskite-silicon modules borrow the best features of both technologies, stacking a perovskite layer atop silicon-based devices for even higher efficiency. TEAMUP argues that combining the two technologies in a tandem solar module design is easier than replacing silicon, as deployment could involve upgrading existing installations. But despite the promise of perovskite materials, technical limitations remain a barrier to commercialization. 

Backed by a $9 million grant from the DOE, TEAMUP will explore key technical gaps in tandem perovskite solar cells—namely, methods to shield perovskite layers from degradation and enhance their stability. The partnership includes participation from the DOE-funded National Renewable Energy Laboratory and four universities: the University of Colorado-Boulder, Illinois-based Northwestern University, Arizona State University, and the University of California-Merced. 

Three companies are involved: Swift Solar, a California-based startup manufacturing lightweight metal halide perovskite tandem cells; Tandem PV, another California company offering perovskite/silicon stacked tandems to upgrade existing silicon systems; and Arizona-based Beyond Silicon, offering a bifacial perovskite/silicon tandem cell to replace silicon PV modules. 

 

Perovskite Efficiency, Instability 

Perovskite solar cells offer power conversion efficiencies competitive with industry-leading solar photovoltaic (PV) systems. According to the DOE, various design advancements have increased the material’s efficiency from 3% in 2009 to 25.7% for single-junction perovskite devices and 29.8% for tandem (stacked) perovskite-silicon devices. 

 

Historical record of efficiency values (as of January 2022) for perovskite cells and other solar photovoltaic technologies, including gallium arsenide cells, crystalline silicon cells, and thin-film cells. Image used courtesy of National Renewable Energy Laboratory

 

Characteristically flexible, perovskite cells can easily be combined with other PV technologies, namely silicon, to reach power conversion efficiencies of over 33%, breaching the theoretical limit of a single junction PV cell. Since perovskite materials can be tuned to respond to various colors in the solar spectrum, they make great candidates for a tandem device setup. 

However, the limited stability of perovskite cells presents a larger challenge. Perovskites tend to decompose in reaction to moisture and oxygen or when exposed to light/heat or applied voltage long-term. As such, more durable components will be required to extend the lifetime of perovskite cells. 

Through the DOE’s Solar Energy Technology Office (SETO), the federal government has invested millions of dollars in researching strategies to lower costs and improve the stability of perovskites, including the $9 million allocated for TEAMUP’s activities. The SETO’s Solar Energy Research Database lists over 80 perovskite projects totaling $109 million in awards since 2014. 

 

The TEAMUP Partnership

The TEAMUP researchers will center their work around three technical challenges: Whether to use monolithic or mechanically stacked tandems for combining perovskite and silicon devices; whether to use vapor or other solutions to process the perovskite layer; and other advancements that can make the tandem devices more stable. 

The partnership will be headed by the University of Colorado-Boulder, under lead investigator Michael McGehee, a chemical and biological engineering professor with extensive experience in solar cell materials. TEAMUP’s industry partners, Swift Solar and Tandem PV, were both started by McGehee’s former students. Beyond Silicon was founded by an electrical engineering professor and a doctoral student at Arizona State University, who developed a perovskite silicon tandem solar cell that reached a record-breaking 23.6% efficiency in 2017—near the then all-time record of 26.3%. 

Arizona State University recently outlined its contribution to the TEAMUP program in a blog post earlier this month. Three research groups will study the damage limits of tandem silicon and perovskite panels, how aging affects the X-ray characterization of micro-level structural strains, and leveraging optoelectronic properties to maximize generation. 

UC-Boulder’s press release says the researchers will pursue a two-stage process. The first will explore different perovskite materials, structures, and fabrication methods. A testing period will follow to simulate the modules’ long-term performance in realistic conditions. Meanwhile, this data will be used to inform forecasting models measuring performance over 25 years.