Transparency

Researchers at the Indian Institute of Technology Bombay have reported NIR-transparent perovskite solar cells (PSCs) with the stable triple cation perovskite as the photo-absorber and subsequent integration with a Si solar cell in a 4T tandem device. The scientists said that the cell provides outstanding stability in the dark, as well as continuous heating conditions.

The top perovskite cell incorporates a room-temperature sputtered transparent conducting electrode (TCE) as a rear electrode. It has an n–i–p structure and utilizes an anti-reflecting coating, an electron transport layer (ETL) made of tin(IV) oxide (SnO₂), a perovskite layer, a molybdenum oxide (MoOx) layer, and a spiro-OMeTAD hole transport layer (HTL). The MoOx buffer layer protects the perovskite photo-absorber and charge transport layers from any sputter damage.

Scientists from Karlsruhe Institute of Technology (KIT) have developed a new way to fabricate micro-patterned translucent perovskite solar cells that could be used in tandem solar modules intended for applications in building-integrated photovoltaics (BIPV). “While translucent perovskite multi-junction devices have been envisaged and recognized as a promising path towards high- efficiency neutral-color transparent PV, the tolerance of complex perovskite tandem stacks against extensive laser scribing has yet to be explored,” the research group said.

The researchers noted that the cells have thus far provided decent levels of power conversion efficiency while maintaining a high average visible transmittance (AVT). They used a custom-built laser scribing setup to fabricate a perovskite solar cell with n–i–p architecture and with an active area of 0.105 cm². The device is based on an indium tin oxide (ITO) substrate, a hole transport layer made of carbazole (2PACz), an electron transport layer made of buckminsterfullerene (C60), an absorber based on methylammonium lead triiodide (CH3NH3PbI3), a bathocuproine (BCP) buffer layer, and a gold (Au) metal contact.

The Indian Institute of Technology Roorkee (IIT Roorkee) and General Insurance Corporation of India (GIC Re) have signed a partnership agreement to develop perovskite-based solar window technology that will enhance the solar power generation in India and lead to greater sustainable development.

The new solar window technology will be designed and developed by Prof. Soumitra Satapathi from the Department of Physics (IIT Roorkee) and his team. Under the program, semi-transparent perovskite solar cells will be developed for building integrated photovoltaics (BIPV). The new window solar technology will harness electricity during the daytime and reduce reliance on traditional electricity sources. 

Researchers from EMPA (Swiss Federal Laboratories for Materials Science and Technology), University of Cantabria and National Tsing Hua University have created a bifacial perovskite-CIGS tandem solar cell and developed a new low-temperature production process resulting in record efficiencies of 19.8% for front and 10.9% for rear illumination.

The idea is collecting direct sunlight, as well as its reflection via the rear end of the solar cell, which should increase the yield of energy the cell produces. Potential applications are, for instance, building-integrated photovoltaics, agrivoltaics – the simultaneous use of areas of land for both photovoltaic power generation and agriculture – and vertically or high-tilt installed solar modules on high-altitude grounds.

An international research group has designed a semi-transparent perovskite solar cell that reportedly shows an improved open-circuit voltage and fill factor thanks to plasmonic enhancement.

The technique is based on the enhancement of the cell's electromagnetic field through metal nanostructures, which improves the device's low optical absorption in the visible spectrum. The research team designed the tech with applications in building-integrated photovoltaics (BIPV) in mind, but it can also be suitable for automotive and smart glasses.

Solliance partners TNO, imec/EnergyVille and the Eindhoven University of Technology, have reported a 18.6% efficient highly near infrared transparent perovskite solar cell. When combined in a four terminal tandem configuration with an efficient Panasonic crystalline silicon (c-Si) cell or with a Miasolé flexible CIGS cell, the configuration delivered new record power conversion efficiencies of 28.7% and 27.0%, respectively.

The researchers explained that four terminal tandems allow to build on experience and practices already available in the industry. In addition, four terminal perovskite/c-Si tandems can be applied broadly and are, for example, very beneficial in combination with bifacial c-Si solar cells which, depending on the actual albedo, can readily achieve a total power generation density as high as 320 W/m².

Scientists from South Korea have developed a foldable thin-film device with promising characteristics. Integrating a perovskite cell material and a carbon nanotube electrode, the group fabricated a device that achieved 15.2% efficiency and could be folded more than 10,000 times at a bending radius of 0.5mm.

Solar cell materials tend to be quite sensitive. Designing and manufacturing devices that can withstand the stress of being folded and bent is challenging, and many of even the most promising solutions are still quite limited in their flexibility. The scientists at Pusan National University in South Korea took a major step forward in solving this problem, fabricating a device that can be folded down to a 'bending radius' ' the minimum size of fold possible without causing damage ' of 0.5mm.

A new EU project called "CITYSOLAR" aims to revolutionize the market for transparent solar cells for windows by combining two photovoltaic (PV) technologies in a tandem configuration. The project has received 3,779,242 EUR in support from the H2020 framework programme. Transparent solar cells for windows have been known for several years, but are still not sufficiently efficient - which is what the new project will attempt to change.

'We develop new innovative concepts within light management and solar module integration that are specifically targeted at new promising organic and hybrid thin film PV technologies, and by that we go significantly beyond state-of-the-art in terms of efficiency for transparent photovoltaics. It's a revolutionary new concept,' says Professor Aldo di Carlo, Cnr-Ism, who is coordinator of the new project and is thrilled about the support of "CITYSOLAR" from the H2020 framework.

Researchers from the Shaanxi Normal University in China have designed a perovskite solar cell based on methylammonium lead iodide (MAPbI₃) through a dual passivation technique that simultaneously passivates trap defects in both the perovskite and electron transport layer (ETL) films.

'So far, most techniques for modifying perovskite solar cells focus on either the perovskite or electron transport layer,' the research group reported, noting that the ETL must have decent optical transmittance and high electron mobility to extract photo'induced carriers and contribute to the solar cell efficiency.

A research team, led by University of Minnesota Professor K. Andre Mkhoyan, has made a discovery that blends the best of two sought-after qualities for touchscreens and smart windows'transparency and conductivity.

The atomic arrangement of both the BaSnO3 crystal and the metallic line defect. Image credit UMN

The researchers have observed metallic lines in a perovskite crystal. Perovskites are abundant in the Earth's center, and barium stannate (BaSnO₃) is one such crystal. However, it has not been studied extensively for metallic properties because of the prevalence of more conductive materials like metals or semiconductors. The finding was made using advanced transmission electron microscopy (TEM), a technique that can form images with magnifications of up to 10 million.