Scientists at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have reported a breakthrough in the development of a next-generation thermochromic window that not only reduces the need for air conditioning but simultaneously generates electricity.

NREL researcher Lance Wheeler holds a perovskite window prototype that can switch between a variety of colors. Photo by Dennis Schroeder, NREL, taken from globenewswire

The technology, dubbed 'thermochromic photovoltaic,' allows the window to change color to block glare and reduce unwanted solar heating when the glass gets warm on a sunny day. This color change also leads to the formation of a functioning solar cell that generates on-board power. Thermochromic photovoltaic windows can help buildings turn into energy generators, increasing their contribution to the broader energy grid's needs. The newest breakthrough now enables various colors and a broader range of temperatures that drive the color switch. This increases design flexibility for improving energy efficiency as well as control over building aesthetics that is highly desirable for both architects and end users.

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have developed a new wide-bandgap perovskite layer – called Apex Flex – which they claim is able to withstand heat, light, and operational tests, and at the same time provide a reliable and high voltage.

With this material, they have built tandem solar cells with 23.1% power conversion efficiency on a rigid substrate, and 21.3% on flexible plastic. The new Apex Flex wide-bandgap perovskite recombination layer is grown with atomic layer deposition (ALD). The new material is described as a “nucleation layer consisting of an ultra-thin polymer with nucleophilic hydroxyl and amine functional groups for nucleating a conformal, low-conductivity aluminum zinc oxide layer.”

The U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) has established a public-private consortium called the US-MAP for US Manufacturing of Advanced Perovskites Consortium, that aims to fast track the development of low-cost perovskite solar cells for the global marketplace.

The joint effort will aim at resolving a number of issues involving manufacturing and durability. US-MAP will also tackle sustainability issues, some of which relate to the use of lead and other metals.

Researchers from Helmhotlz-Zentrum Berlin (HZB), collaborating with teams from University of Cambridge, Eindhoven University of Technology, Nicolaus Copernicus University, Salerno University and others, have developed a monolithic "two-terminal" tandem cell made of CIGS and perovskite that achieved a certified efficiency of 24.16%, with a thickness of well below 5 micrometers - which would allow the production of flexible solar modules.

Tandem cells combine two different semiconductors that convert different parts of the light spectrum into electrical energy. Metal-halide perovskite compounds mainly use the visible parts of the spectrum, while CIGS semiconductors convert rather the infrared light. CIGS cells, which consist of copper, indium, gallium and selenium, can be deposited as thin-films with a total thickness of only 3 to 4 micrometers; the perovskite layers are even much thinner at 0.5 micrometers.

Researchers from Colorado University in Boulder with the US Department of Energy's National Renewable Energy Laboratory (NREL) have shown how a change in chemical composition managed to boost the longevity and efficiency of a perovskite solar cell.

The new formula reportedly enabled the solar cell to resist a stability problem that has so far thwarted the commercialization of perovskites. The problem is known as light-induced phase-segregation, which occurs when the alloys that make up the solar cells break down under exposure to continuous light.

Researchers at Northern Illinois University and the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) in Colorado have reported on a potential breakthrough in the development of hybrid perovskite solar cells.

Led by Tao Xu of NIU and Kai Zhu of NREL, the scientists have developed a technique to sequester the lead used to make perovskite solar cells and minimize potential toxic leakage by applying lead-absorbing films to the front and back of the solar cell.

Hunt Perovskite Technologies (HPT), a Texas-based perovskite applications developer, has reported a milestone in the development of a highly-durable perovskite technology for the manufacture of low-cost printed solar cells.

In December 2019, HPT demonstrated that its ink-based process was able to produce a perovskite solar cell that exceeded key benchmarks recognized by the solar cell manufacturing industry and exceeded the International Electrotechnical Commission (IEC) durability thresholds in temperature, humidity, white light and ultraviolet (UV) stress testing while reaching efficiency performance levels of 18%.

The groups of Steve Albrecht and Bernd Stannowski at HZB have reached a record efficiency of 29.15% of its tandem solar cell made of perovskite and silicon.

The illustration shows the structure of the tandem solar cell: between the thin perovskite layer (black) and the silicon layer (blue) are functional intermediate layers. © Eike Köhnen/HZB

This value has been officially certified by the CalLab of the Fraunhofer Institute for Solar Energy Systems (ISE) and means that surpassing the 30% efficiency mark is now within reach.

Researchers at the National Renewable Energy Laboratory (NREL) report the creation of an efficient tandem perovskite solar cell, using a new chemical formula which also improved the structural and optoelectronic properties of the solar cell.

Most of the research efforts in the field of PSCs have focused on lead-based perovskites, which have a wide bandgap. High efficiency, low bandgap perovskites would enable the fabrication of very high efficiency all-perovskite tandem solar cells where each layer absorbs only a part of the solar spectrum and is optimally configured to convert this light into electrical energy. However, low bandgap perovskites have long suffered from large energy losses and instability limiting their use in tandems.

Researchers at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have reported the development of an environmentally-stable perovskite solar cell that reportedly maintained 94% of its starting efficiency after 1,000 hours of continuous use under ambient conditions.

'During testing, we intentionally stress the cells somewhat harder than real-world applications in an effort to speed up the aging,' says an involved researcher at NREL. 'A solar cell in the field only operates when the sun is out, typically. In this case, even after 1,000 straight hours of testing the cell was able to generate power the whole time.'