Efficiency - Page 36

Researchers from The University of Queensland, EPFL, Griffith University and NIMS have studied how doping can help in overcoming some of perovskite solar cells' drawbacks. The researchers found that the efficiency and thermal stability of the doped cells significantly outperformed those that were not doped.

“The PSCs that had doped cells showed a remarkable solar conversion efficiency that exceeded 21 per cent,” the team reported.

Researchers from Princeton University have summarized the advancements in using molecular dopants to control the electronic structure of metal halide perovskites. They provide an overview of fundamental work on this doping method for interfaces and adjacent transport layers, which play a predominant role in the design, performance, and stability of perovskite solar cells.

'The development of perovskite technology requires control of the electronic properties, and one of the ways is to dope the material to make it more electron-rich or hole-rich,' said author Antoine Kahn. 'Doping of the bulk of these materials is still in its infancy. It's actually quite difficult to achieve, but a somewhat successful way is to use molecular organic dopants at interfaces.'

Scientists from École Polytechnique Fedérale de Lausanne (EPFL), University of Luxembourg, Empa-Swiss Federal Laboratories for Materials Science and Technology and CNRS have demonstrated a simple approach to designing the interface between two layers in a perovskite solar cell, improving both the performance and stability of the device.

Solar cells fabricated by the group achieved 23.4% conversion efficiency, and were operated for close to 6,000 hours before degrading beyond 80% of this initial value.

Researchers from Russia-based ITMO University and the University of Rome Tor Vergata have developed a paste made of titanium dioxide (TiO₂) and resonant silicon nanoparticles, claimed to improve light absorption in perovskite solar cells based on methylammonium lead iodide (MAPbI₃).

The scientists created a mesoporous electron transport layer based on optically resonant silicon nanoparticles which were then incorporated into TiO₂ paste. 'Such particles serve as nanoantennae ' they catch light and it resonates inside them. And the longer light stays in the photoactive layer, the more of it is absorbed by the material,' said Sergey Makarov, professor at ITMO's school of physics and engineering.

Skoltech researchers, along with colleagues from the RAS Institute for Problems of Chemical Physics, have synthesized a new conjugated polymer for organic electronics using two different chemical reactions and shown the impact of the two methods on its performance in organic and perovskite solar cells.

Perovskite solar cells have reached impressive certified record efficiencies, but long-term stability remains an issue. Recent research has shown that device stability can be improved by covering the photoactive perovskite material with a charge-extraction layer that provides efficient encapsulation. Among other materials, this protective function may be fulfilled by conjugated polymers.

Researchers from ITMO's School of Physics and Engineering have created a paste, made of titanium dioxide and resonant silicon nanoparticles, meant to increase the generation of photocurrent in perovskite solar cells and maximize their efficiency.

Image by ITMO

One of two strategies is usually used to further boost the efficiency of PSCs: improving the charge collection or increasing light absorption by the charge generating layer. The first strategy also means the need to introduce other substances or 2D structures into perovskites, which makes the resulting devices more expensive. The ITMO team, together with colleagues from Tor Vergata University, went around this problem by using Mie-resonant silicon nanoparticles, as silicon is one of the elements most accessible in nature.

Japan-based global electronics giant Toshiba recently announced a 15.1% power conversion efficiency for a 703cm² polymer film-based perovskite solar module. The result is referred to by the company as 'the highest efficiency yet reported for any large, polymer film-based perovskite photovoltaic module'.

The device was created using a one-step coating method that uses improved ink, film drying processes, and production equipment to form a uniform perovskite layer. The process is said to reduce the number of steps needed for deposition of the MAPbI₃ perovskite layer. The coating speed is said to reach six meters per minute on a 5×5 cm² module, which the company defined as a rate that meets requirements for mass production.

Scientists from China's Nanjing University and Chinese Academy of Sciences have found that a change to the hole transport layer material helped reduce voltage loss in a perovskite solar cell. The discovery demonstrates a promising new way to overcome a major challenge for perovskites ' particularly those used as the top layer in a tandem device.

The group of scientists noticed that a large part of the problematic voltage loss occurs at the interface between the active perovskite and the hole transport layer (HTL) that helps to carry a charge out of the device, and decided to experiment with alternate materials to try and limit this issue.

Researchers from Sungkyunkwan University and Pusan National University recently succeeded in complementing an intrinsic defect of a perovskite solar cell's absorber layer by adding a virus. The team showed that the efficiency of photoelectric transformation improved by using a virus rather than a chemical compound as solar cell thin film.

Solar cells based on perovskites as an absorber layer usually require the addition of a chemical compound due to intrinsic defects of perovskite crystal. Perovskite solar cells are limited as the process of adding chemical compounds is expensive and the purity of the generated material is low.

Scientists from Oxford PV have recently published a study describing how pairing metal halide perovskites with conventional silicon leads to a more powerful solar cell that overcomes the 26% practical efficiency limit of using silicon cells alone.

'We identified perovskites as the perfect partner for a tandem system with silicon,' commented author Laura Miranda Pérez.