Solar cells have traditionally occupied vast outdoor areas. Though they are essential to averting the worst effects of climate change, they are often seen as an eyesore.
A team of scientists from National Yang Ming Chiao Tung University in Taiwan has created solar cells that effectively convert indoor lighting into electrical power.
This potentially opens the door to solar panels in indoor spaces. These could reduce power consumption by producing power from standard lighting. The new development could also allow solar panels to produce energy even on cloudy days.
New indoor solar cells
Perovskite solar cells (PeSCs) are a lower-cost, higher-efficiency alternative to traditional silicon solar cells.
PeSCs have a high power conversion efficiency rate (PCE). This refers to the energy created from the energy hitting the cell. Overall, the high efficiency of PeSCs makes them ideal for converting low light levels to energy.
In a paper published in APL Energy, the National Yang Ming Chiao Tung University scientists detailed their new PeSCs. They built on previous research, which shows PeSCs can achieve PCE rates comparable to silicon solar cells while working.
“The most common PeSCs in the market are silicon-based solar panels,” author Fang-Chung Chen explained in a press statement. “However, PeSCs can be made thin, lightweight, flexible, and even semi-transparent, whereas silicon panels are rigid and heavy, which limits their use to flat, durable surfaces.”
The team tested their PeSCs, showing promising results. Under one standard sun illumination (roughly 12,000 lux), the team’s perovskite cells achieved a PCE of 12.7%. This is relatively low compared to the 26% PCE of some of the highest performing silicon solar cells. However, under a much lower 2,000 lux, the PeSCs displayed an impressive PCE of 38.7%. 2,000 lux is roughly the brightness level found in a standard office space.
Drawing energy on cloudy days
To develop their solar cell, the researchers altered the bandgap of the composition of their perovskite. Band gaps refer to the minimum energy necessary for electrons to jump into higher energy levels.
The team adjusted the ratios of the molecules in solutions used to make the perovskite layers of the solar cells. By doing this, they achieve a bandgap that allows their solar cells to absorb indoor light. This particular bandgap is not possible in silicon solar cells.
“The indoor efficiency of PeSCs is higher, meaning that the photovoltaic products can be more suitable for versatile user scenarios, including cloudy outdoor, indoor, and other dim-light environments,” said Chen.
According to the team, their PeSCs could be used to charge small devices in areas that don’t have access to sunlight.