Perovskite is one of the most exciting materials for making better solar photovoltaic (PV) cells. It is a naturally occurring mineral, but also can be synthesized from abundant and cheap chemicals. Perovskite solar cells can be fine-tuned to absorb different colors of the solar spectrum, converting sunlight to energy with high efficiency. They can also be produced at a low cost with relatively simple machinery and processes. Silicon has been the dominant material in solar cells for decades. But silicon PV technology is reaching its practical efficiency limits. Perovskite solar cells could be a game-changer, offering the tantalizing possibility of more efficient, cheaper solar power.
Two major types of perovskite solar cells have been developed over recent decades: single-layer, thin-film perovskite solar cells and perovskite tandem solar cells.
Figure 1: Thin-film perovskite solar cells developed by the Korea Research Institute of Chemical Technology
Thin-film perovskite solar cells use a single layer of perovskite material to convert light to usable energy. Figure 1 shows thin-film perovskite solar cells developed by the Korea Research Institute of Chemical Technology that are about 200 times thinner than traditional silicon solar cells. Thin-film perovskites could potentially penetrate the market for building-integrated PV (i.e., roofs and windows that could generate power), eliminating the need to devote large land areas to solar farms while drastically downsizing the impact on the power grid.
Perovskite tandem solar cells place a perovskite layer over a layer of perovskite, silicon, or other PV materials. Perovskite has a flexible bandgap, allowing it to absorb different parts of the solar spectrum to provide greater combined efficiencies with other PV materials. When paired with silicon—which has an inflexible bandgap—solar cells could reach over 30 percent efficiency.
To achieve net-zero emissions globally, the International Energy Agency finds that solar PV must become the largest power source by 2050. By 2030, 630 gigawatts (GW) of annual solar capacity additions will be needed, nearly four times the record levels set in 2020. While silicon solar cells currently dominate the market—taking around 95 percent of the market share—silicon is not the best solar material. It has an efficiency limit of about 30 percent, is thick and bulky, and is made through a complex and energy-intensive process. The U.S. Department of Energy’s (DOE’s) Solar Futures Study finds that new PV cell technologies are essential to compensate for the limits of silicon.
Perovskite solar cells could be the high-efficiency PV technology the world needs to drive down solar PV costs aggressively. In March 2021, DOE’s SunShot Initiative announced an ambitious target to reduce utility-scale solar PV costs by more than half by 2030. DOE identifies two technology trajectories to reach this goal:
- The high-performance scenario assumes novel high-efficiency solar cells will reduce the levelized cost of energy (LCOE) of solar PV through higher energy yields and reliability (i.e., longer service life).
- The low-cost scenario assumes existing solar cells will continue their downward cost trends, and LCOE reductions will mainly come from non-cell components of a PV system (see figure 2).
DOE’s Solar Futures Study finds that perovskite could contribute to the high-performance scenario, pushing down costs by enabling the production of more power per solar panel.
Figure 2: Two example cases that achieve the 2030 target for utility-scale PV LCOE
The production process of perovskite solar cells is much simpler as well. Producing silicon solar cells involves refining silicon under high heat, infusing it with other materials, and slicing it into wafers. On the other hand, perovskite solar cells can be made at low temperatures and used in liquid form to coat flexible materials like plastic, enabling a roll-to-roll manufacturing process like newspaper printing (figure 3). Tandem perovskite-on-silicon solar cells create the opportunity to maintain the existing silicon production process to maximize the chance of market acceptance and avoid additional capital costs.
Figure 3: Perovskite solar cells printed on thin films developed by Swansea University researchers