Researchers pinpoint surprising cause of efficiency loss in solar cells based on hybrid perovskites

Researchers at UC Santa Barbara have discovered an important factor that limits the efficiency of perovskite solar cells.

Various possible defects in the lattice of hybrid perovskites had previously been considered as the potential cause of such limitations, but it was assumed that the organic molecules would remain intact. The team has now revealed that missing hydrogen atoms in these molecules can cause massive efficiency losses.

KIT researchers demonstrate high efficiency over large area perovskite solar module

Researchers at the Karlsruhe Institute of Technology (KIT) have produced perovskite solar modules with greatly reduced loss of efficiency due to scaling. The team reported an efficiency of 18% for a perovskite solar module with an area of ​​4cm2 - a world record for vacuum-processed perovskite solar modules. To this end, they combined the series connection by laser with the vacuum processing of all layers of the solar cell.

Interconnecting cells into modules with almost no losses is achieved with an innovative combination of processes image

"One of the main challenges is to transfer the efficiencies achieved on areas of a few square millimeters to typical solar module surfaces of a few hundred square centimeters," says Dr. Tobias Abzieher, who heads the development of perovskite solar cells deposited from a vacuum at the Light Technology Institute (LTI) of the KIT. Perovskite solar cells are often joined together to form large-area solar modules using the so-called monolithic series connection. For this purpose, structuring lines are introduced during the deposition of the individual layers of the solar cell, which causes the solar cell strips to be connected in series.

Solliance partners reach new efficiency record with four terminal tandem configurations

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.

Novel ETL shows promise for efficient and stable perovskite solar cells

Researchers from the Chinese Academy of Sciences (CAS) and Fuzhou University have reported a perovskite solar cell with an electron transport layer (ETL) based on Tin(IV) oxide (SnO2) and crystalline polymeric carbon nitrides (cPCN).

The team explained that the modification of the SnO2 layer with the cPCN is key to avoiding undesirable current-voltage hysteresis, which is responsible for reducing the cell's stability. This phenomenon tends to occur in electrical systems when current or voltage changes and the effects of the changes are delayed. It is dependent on the composition of the material, and ion migration and non-radiative recombination near interfaces are often considered responsible for the effect.

Carbon dot-wrapped perovskites could enable stable and efficient PSCs

Researchers from Australia's Queensland University of Technology (QUT) and Swinburne University of Technology have reported the creation of resilient, high-efficiency triple-cation perovskite solar cells (PSCs) by incorporating carbon dots (CDs) derived from human hair into the perovskite film.

QUT's Professor Hongxia Wang’s team had previously found that nanostructured carbon materials could be used to improve a cell’s performance. In their recent work, they tried using the carbon nanodots on perovskite solar cells. After adding a solution of carbon dots into the process perovskites synthesis, Professor Wang’s team found the carbon dots forming a wave-like layer where the perovskite crystals are surrounded by the carbon dots.