Efficiency - Page 55

A team of researchers from Peking University and the Universities of Surrey, Oxford and Cambridge have developed a new way to reduce an unwanted process called non-radiative recombination, where energy and efficiency is lost in perovskite solar cells. This technique has reportedly produced "the highest performing inverted perovskite solar cell ever recorded".

The team created a technique called Solution-Process Secondary growth (SSG) which increased the voltage of inverted perovskite solar cells by 100 millivolts, reaching a high of 1.21 volts without compromising the quality of the solar cell or the electrical current flowing through a device. They tested the technique on a device which recorded a PCE of 20.9%, which is said to be the highest certified PCE for inverted perovskite solar cells ever recorded.

Oxford Photovoltaics has reported a new perovskite tandem solar cell record, certified by Fraunhofer ISE at a conversion efficiency of 27.3%. Oxford PV's latest record for a 1 cm² perovskite-silicon tandem solar, reportedly exceeds the 26.7% efficiency world record for a single-junction silicon solar cell.

Oxford PV recently produced a 1 cm² perovskite-silicon two-terminal tandem solar cell with a verified conversion efficiency of 25.2%, through an ongoing collaboration with Helmholtz-Zentrum Berlin (HZB) and the Photovoltaics and Optoelectronics Device Group at the University of Oxford, led by Professor Snaith.

Oxford Photovoltaics, in collaboration with Helmholtz-Zentrum Berlin (HZB) and the Photovoltaics and Optoelectronics Device Group at the University of Oxford, produced a 1 cm² perovskite-silicon two-terminal tandem solar cell with a verified conversion efficiency of 25.2%. The two-terminal tandem solar cell efficiency was certified by the Fraunhofer Institute for Solar Energy Systems ISE.

Dr Chris Case, Chief Technology Officer at Oxford PV commented, 'The unique, optically enhanced architecture developed as part of this collaboration, minimizes losses, and has helped us achieve this record setting efficiency'.

EPFL the CSEM PV-center researchers have combined silicon and perovskite to create solar cells with the resulting efficiency of 25.2%, in what is regarded as a record for this type of tandem cell. Their innovative yet simple manufacturing technique could be directly integrated into existing production lines, and efficiency could eventually rise above 30%.

The researchers explain that creating an effective tandem structure by superposing two materials is no easy task. "Silicon's surface consists of a series of pyramids measuring around 5 microns, which trap light and prevent it from being reflected. However, the surface texture makes it hard to deposit a homogeneous film of perovskite," explains Quentin Jeangros, who co-authored the paper. A common problem in such cells arises from the fact that when the perovskite is deposited in liquid form, it accumulates in the valleys between the pyramids while leaving the peaks uncovered, leading to short circuits. The team tackled this problem by using evaporation methods to form an inorganic base layer that fully covers the pyramids. That layer is porous, enabling it to retain the liquid organic solution that is then added using a thin-film deposition technique called spin-coating. The researchers subsequently heat the substrate to a relatively low temperature of 150°C to crystallize a homogeneous film of perovskite on top of the silicon pyramids.

Saule Technologies, Poland-based developer of perovskite solar cells ink-jet printed on thin foil, has issued an open call for companies interested in licence agreements for BIPV applications in Middle Eastern countries. This follows Saule's recent announcement of the first commercial contract in BIPV with Norwegian construction company Skanska.

Saule Technologies offers flexible licence-based cooperation opportunities for companies active in the Middle East, available for entities interested in the development, distribution and integration of Saule's solar cells in BIPV applications. The subject of the licence is an opaque PV product with very high energy conversion efficiency which can be easily integrated with building facades, and an efficient, translucent perovskite cell in any color (so-called "solar window"). Conditional licence (Exclusive Licence and Non-Exclusive Licence) for the use of any future product can be granted for a chosen country or group of countries not covered by the licence agreement with another entity.

A multi-institutional team of researchers from the Department of Energy's Oak Ridge National Laboratory, Hunan University and the University of Nebraska'Lincoln used photoluminescence measurements, along with neutron and x-ray scattering, to study the relationship between hybrid perovskite materials' microscopic structure and optoelectronic properties. Neutron scattering has revealed, in real time, the fundamental mechanisms behind the conversion of sunlight into energy in such materials, to gain a better understanding that will enable the design of better solar cells.

By examining the material under varying degrees of temperature, the researchers were able to track atomic structural changes and establish how hydrogen bonding plays a key role in the material's performance. Unlike their singular silicon or germanium counterparts, hybrid perovskites are made of both organic and inorganic molecules. 'The advantage of having both organic and inorganic molecules in a well-defined crystal structure means we can tailor the material by tuning either one group or the other to optimize the properties,' said Kai Xiao, a researcher at ORNL's Center for Nanophase Materials Sciences. 'But even though researchers have been studying these materials for several years, we still don't fully understand on a fundamental level how the organic components are affecting the properties.'

Imec, the leading research hub focused on nanoelectronics, energy and digital technologies and partner in EnergyVille, has been named the coordinator of an ambitious 3-year European Union (EU) funded project called "ESPResSo" (Efficient Structures and Processes for Reliable Perovskite Solar Modules), that gathers known leaders in the field of perovskite PV technology to revolutionize Europe's photovoltaics (PV) industry.

The ESPResSo consortium has been granted over 5 Million by the European Union to overcome the limitations of today's state-of-the-art perovskite PV technology, bring perovskite solar cells to the next maturity level, and demonstrate their practical application.

Researchers at Aalto University in Finland have designed a new, simplified method for testing solar cells based on perovskite and dye sensitized technologies for degradation. This presumably follows Aalto's findings from February 2018 regarding deficiencies in current aging tests performed on perovskite-based solar cells.

The researchers explain that their fast, low threshold photography method could detect even slight disintegration in a perovskite structure, with more reliable results than optical measurement devices, and lower complexity and labor requirements than more commonly used x-ray crystallography.

Solliance announced a new record stabilized average cell performance of 14.5% for its large thin-film perovskite photovoltaic modules on glass. The efficiency was measured on an aperture area of 144 cm².

The perovskite module was realized on a commercial 6x6 inch² glass substrate, a size comparable to standard commercial silicon solar cells. The substrate is provided with a transparent conductor, by applying three consecutive slot die coating processes and using a newly developed annealing process. The metal top electrode was evaporated. Twenty-four cells were series-connected through optimized laser-based scribes. Up to 95.3% of the modules area is covered with active material, resulting in a stabilized module efficiency of 13.8%.

A collaboration led by Rice University and Los Alamos National Laboratory has found that constant illumination reduces strain in a perovskite crystal lattice, and allows it to uniformly expand in all directions.

The expansion was found to improve the conversion efficiency, 'curing' defects in the crystal structure and allowing more electrons to move through the material. The researchers modeled over 30 iodide-based thin films with perovskite-like structures, and found that when exposed to light, the bonds between atoms relaxed and barriers between the perovskite layer and the electrode largely vanished.