March 2017

Researchers from Aalto University, Uppsala University and École polytechnique fédérale de Lausanne (EPFL) in Switzerland have managed to improve the long term stability of perovskite-based solar cells by using a carbon nanotube film to replace the gold used as the back contact and the organic material in the hole conductor.

To conduct the study, thick black films with high conductivity were used in the back contact of the solar cell where light does not need to get through. Nanotube films can also be made transparent and thin, which would make it possible to use them as the front contact of the cell. The solar cells were prepared in Uppsala and the long-term stability measurement was carried out at EPFL.

Microquanta Semiconductor, a China-based thin-film PV firm, has announced a new efficiency record for perovskite mini-modules: 15.24%, certified by Newport PV Lab in Montana, US. The tested mini-module has an aperture size of more than 16 cm².

Microquanta said that by passing the 15% efficiency milestone for the first time, it has moved significantly closer towards commercialization of perovskite solar cells. It also claimed that perovskite mini-modules are desirable since they can reduce the manufacturing cost of current c-Si based solar cells by between 60-80%.

Researchers at Los Alamos National Laboratory and their partners are creating innovative 2D layered hybrid perovskites that they say can allow greater freedom in designing and fabricating efficient optoelectronic devices. Industrial and consumer applications could include low cost solar cells, LEDs, laser diodes, detectors, and other nano-optoelectronic devices.

They explain that these materials are layered compounds, or a stack of 2D layers of perovskites with nanometer thickness (like a stack of sheets), and the 2D perovskite layers are separated by thin organic layers. "This work could overturn conventional wisdom on the limitations of device designs based on layered perovskites", the team says.

Solliance, a partnership of R&D organizations from the Netherlands, Belgium and Germany working on thin film photovoltaic solar energy, recently demonstrated an industrially-applicable roll-to-roll process for the production of solar cells achieving a record 12.6% conversion efficiency on cell level. This result allows for an accelerated market introduction of this attractive new source of renewable energy.

The roll-to-roll (R2R) process was developed for both the electron transport and the perovskite layers on the new Solliance dual R2R coating line. The in-line roll-to-roll coating, drying, and annealing processes were executed at a linear speed of 5m/min on a 30-cm wide commercial PET/ITO foil and under ambient conditions. All process steps on this roll-to-roll line were performed using low-cost materials while keeping the process temperatures below 120 ⁰C, which is indicative of the production potential of this new emerging thin film PV technology.

A team of researchers from the University of Macau (UM), Nanjing Tech University, and Nanyang Technological University, Singapore, has announced a significant breakthrough, laying a theoretical foundation for high-efficiency and low-cost perovskite light emitting diode (LED). The research is said to be able to significantly improve the luminous efficiency of perovskite LED and have the potential to advance low-cost, high-efficiency LED displays and LED light sources.

The team discovered that the slow bimolecular recombination that drives 3D lead-halide perovskites' excellent photovoltaic performance is conversely a fundamental limitation for electroluminescence. The team found that the slow bimolecular recombination limitation can be overcome so that high-efficiency electroluminescence can be achieved.

Researchers at the Centre for Hybrid and Organic Solar Energy (CHOSE) of the University of Rome 'Tor Vergata', along with researchers at the Italian Institute of Technology (IIT) and the University of Applied Sciences in Crete (TEI), have stated that they set a new record for conversion efficiency of a perovskite photovoltaic module with an area larger than 50 cm2.

The success was achieved as part of Graphene Flagship, the 1 billion euro European project that promotes graphene-based innovation in sectors like energy, electronics, technology and medicine. Perovskites photovoltaic modules' efficiency is usually demonstrated in the laboratory on cells less than 1 cm2 in size, whereas the new test was performed on modules with an area larger than 50 cm2. The electronic and chemical properties offered by graphene have made it possible to overcome the many difficulties related to the realization of large-area perovskite solar panels.

A team of researchers from the U.S-based Georgia Institute of Technology have designed ultrafine perovskite nanofibers as highly efficient and stable catalysts for OER - oxygen evolution reaction, a component reaction of the electrochemical splitting of water into hydrogen and oxygen. Water splitting is a key step in a number of sustainable energy technologies including hydrogen production, fuel cells, and rechargeable metal-air batteries.

The OER takes place at the anode of an electrolyzer, while the hydrogen evolution reaction takes place at the cathode. The energy required for the reaction is supplied by an electronic current. Currently, a large overpotential is required to accelerate the OER. For this reason, water splitting technologies for hydrogen production are not very competitive as the increased energy required results in more expensive hydrogen compared with production from natural gas. Therefore, much research is focused on the search for cost-effective, efficient and stable catalysts for the OER that can reduce the required overpotential. The new research highlights the potential of doped double perovskite nanofibers as the next generation of OER catalysts.