March 2016

A team of Cambridge scientists, in collaboration with Oxford University AMOLF FOM Institute in Amsterdam, could lead to a revolution in the efficiency of solar power, with the development of perovskite-based panels capable of 'recycling light'.

Solar cells work by absorbing photons from the sun to create electrical charges. However, the process also works in reverse, because when the electrical charges recombine, they can create a photon. The research shows perovskite cells have the extra ability to re-absorb these regenerated photons ' a process known as "photon recycling".

EPFL researchers have achieved the highest yet reproducibility for perovskite solar cells combined with 21.1% efficiency at normal operating conditions, in a cesium-containing perovskite cell. By adding cesium, the EPFL scientists made the first ever triple-cation perovskite mixture (Cs/MA/FA).

The new films are more heat-stable and less affected by changing surrounding variables such as temperature, solvent vapors or the heating protocol used for the device. More importantly, they also show stabilized power-conversion efficiencies of 21.1% and outputs at 18% under operational conditions, even after 250 hours. The researchers regard this as "an absolute breakthrough' and state that these properties are crucial for commercializing perovskite photovoltaics, especially since reproducibility and stability are the main requirements for cost-effective large-scale manufacturing of perovskite solar cells.

A team of scientists from Hokkaido University and the global electronics company TDK Corporation in Japan has developed a method to improve the insulating properties of certain perovskites for potential use as ceramic capacitors.

Ceramic capacitors are used in a wide variety of electronics, ranging from computers and mobile phones to telecommunications transmitter stations and high voltage laser power supplies. Capacitors are dielectric, and act as electronic insulators in which an electric field can be sustained with minimum loss of power. Their dielectric properties allow them to store electricity and then release it. One of the most widely used ceramics in capacitors is lead zirconate titanate, but it is hazardous to the health and the environment once it's disposed. Scientists are trying to find other less hazardous ceramic materials for use in capacitors.

Solliance, a partnership of European R&D organizations working in thin film solar energy, recently announced that Panasonic has joined its research program concerning the development of roll-to-roll manufacturing processes aimed at large scale production of flexible perovskite solar cells as one of the industrial partners.

Research will be carried out at the Solliance pilot production facilities on the High Tech Campus in Eindhoven, the Netherlands, and in the research facilities of imec in Leuven, Belgium. Panasonic will conduct the feasibility studies on the possibility of large scale roll-to-roll production of printed PSCs under this program. This partnership will create a technically capable and commercially focused effort to roll out this next generation technology.

Researchers at the University of Toronto in Canada and ShangaiTech University in China have succeeded in using colloidal quantum dots in a high-mobility perovskite matrix to make a near-infrared (NIR) light-emitting diode (LED) with a record electroluminescence power conversion efficiency of nearly 5% for this type of device. The NIR LED could find use in applications such as night vision devices, biomedical imaging, optical communications and computing.

The researchers say that they may have found a way to overcome the known problem of low power conversion efficiencies (PCEs) of CQD-based LEDs, by embedding CQDs in a high-mobility mixed-halide perovskite matrix. The new composite allows for radiative recombination in the quantum dots by preventing charge carriers from becoming trapped in defects as they travel through the material, and this without increasing the turn-on voltage in a device. By carefully engineering the composition of the mixed halide matrix, the researchers made bright NIR CQD LEDs with electroluminescence PCEs of 4.9%. This value is said to be more than twice that of previously reported values for devices made from these materials, which means that with same amount of electricity it is possible to get twice as much NIR light power out.

A team coordinated by the Centre Suisse d'Electronique et de Microtechnique (CSEM) will work on a €5 million, three-year project to produce solar cells based on perovskite at a size of at least 15x15 cm, while maintaining a conversion efficiency of at least 14%.

In addition to this up-scaling, the research team will develop high-performance cells. Such tandem cells can harvest a broader spectrum of light than a single cell, which should lead to an increase in their efficiency further, approaching the 30% range. The team states that, in the longer term, existing manufacturing methods used to make silicon cells may require only minor modification before being used to produce tandem cells, as the perovskite layer would simply be added on top of the conventional cell to act as an 'efficiency booster'.

Dyesol's UK branch has joined the GOTsolar project, part of the Horizon 2020 program. GOTsolar is a new project which started in January 2106, and Dyesol will be cooperating with partners in Portugal, Switzerland and Poland, as one of seven members of the GOTSolar consortium.

High efficiency perovskite-based solar devices will be fabricated and hermetically encapsulated using a new laser-assisted encapsulation process to enable high durability. These devices will be tested under accelerated aging conditions to validate the new process and to demonstrate the scalability of technologies developed as part of the project. This, according to the company, forms a key aspect of Dyesol's roadmap for metal based flexible modules with 20 years of lifetime.