Achieving 26.0% efficient monolithic perovskite silicon tandem solar cells and analyzing the performance as a function of photocurrent mismatch

Researchers from Helmholtz-Zentrum Berlin (HZB), Eindhoven University of Technology and Technical University Berlin have combined rear junction silicon heterojunction bottom cells with p–i–n perovskite top cells into highly efficient monolithic tandem solar cells with a power conversion efficiency (PCE) of 26.0%.

The influence of current mismatch on device performance in tandem perovskite silicon solar cells imageColored cross sectional SEM image of the top cell (upper panel) and back side of the bottom cell (lower panel) of a typical monolithic tandem solar cell used in this work. (b) schematic device layout of the tandem architecture utilized in this work.

Starting from a certified efficiency of 25.0%, further improvements have been reached by reducing the current mismatch of the certified device. The top contact and perovskite thickness optimization allowed increasing the JSC above 19.5 mA cm−2, enabling a remarkable tandem PCE of 26.0%, however with a slightly limited fill factor (FF).

Collaborative team makes a major step forward in the search for stable and practical perovskite-based photovoltaic devices

A collaborative research team from Los Alamos National Laboratory, Rice University, Purdue University, Northwestern University, Institut FOTON CNRS UMR 6082 (France) and Argonne National Laboratory has created a number of hybrid perovskite solar cells with a FA0.7MA0.25Cs0.05PBI3 composition and measured them using a variety of techniques including grazing-incidence wide-angle x-ray scattering (GIWAXS) maps at the X-ray Science Division 8-ID-E x-ray beamline of the APS (an Office of Science user facility at Argonne).

casts light on new benefits of perovskite solar cells imageThe experimental setup (top left) and the corresponding light-induced lattice expansion effect, which leads to curing defects and relieving of lattice strain (bottom left) and as a result an increase in the open circuit voltage of a solar cell

In most of the cells, the researchers noted a substantial improvement in PCE from 18.5% to 20.5% under continuous light soaking with a 1-sun (100 mW/cm2) source as the lattice structure of the hybrid cells uniformly expanded. This expansion relieved local strains in the bulk material and better aligned the crystal planes, as evidenced by narrowing and uniform shifting of the Bragg peaks toward lower scattering values as seen by GIWAXS. The researchers explain that constant illumination generates electron-hole pairs in the perovskite material, decreasing the distortions of some bonds while elongating others, resulting in a generalized lattice expansion and relaxation. A similar phenomenon was seen with pure MAPbI3 thin films, suggesting that such lattice expansion under light is common for hybrid perovskite materials.

University of Toronto researchers create a more stable electron selective layer for PSCs and tandem solar cells

Researchers at the University of Toronto have designed a method of growing a more stable electron selective layer for perovskite solar cells and tandem solar cells combining crystalline silicon with perovskite.

University of Toronto researchers make Quantum Dots and Perovskite Solar Cells at 150°C image

Perovskite raw materials can be mixed into a liquid in a kind of ‘solar ink.’ This solar ink could be printed onto glass, plastic or other materials with a relatively simple inkjet printing process. However, in order to generate electricity, electrons excited by solar energy from perovskite cells must be extracted from a layer of quantum dots that is held together by a passivation layer. Some types of quantum dots are known to change their 3D structure even at room temperature, making them transparent and ineffective. This passivation layer is also known to break down at temperatures above 100°C. The team’s breakthrough made both quantum dots and perovskites more stable when combined than they are separated and the solar cell combining of Perovskite material and quantum dots achieved 20.1% efficiency.

KAUST team reports 26.2% PCE for 4T perovskite/silicon tandems enabled by IZRO electrodes

Parasitic absorption in transparent electrodes is one of the main roadblocks to enabling power conversion efficiencies (PCEs) for perovskite‐based tandem solar cells beyond 30%. To reduce such losses and maximize light coupling, the broadband transparency of such electrodes should be improved, especially at the front of the device.

Improves NIR response in si/per tandems image

Erkan Aydin and coworkers from KAUST Photovoltaics Laboratory have recently shown the excellent properties of Zr‐doped indium oxide (IZRO) transparent electrodes for such applications, with improved near‐infrared (NIR) response compared to conventional tin‐doped indium oxide (ITO) electrodes. Optimized IZRO films feature very high electron mobility (up to ≈77 cm2 V−1 s−1), enabling highly infrared transparent films with a very low sheet resistance (≈18 Ω −1 for annealed 100 nm films). For devices, this translates to a parasitic absorption of only ≈5% for IZRO within the solar spectrum (250–2500 nm range), to be compared with ≈10% for commercial ITO.

University of Toledo team reports breakthrough in new material for all perovskite tandem solar cells

Researchers from the University of Toledo have reported progress that may push the performance of tandem perovskite solar cells to new levels. Working in collaboration with the U.S. Department of Energy's National Renewable Energy Lab and the University of Colorado, Dr. Yanfa Yan, UToledo professor of physics, envisions that the new high efficiency tandem perovskite solar cell will be ready to debut in full-sized solar panels in the consumer market in the near future.

"We are producing higher-efficiency, lower-cost solar cells that show great promise to help solve the world energy crisis," Yan said. "The meaningful work will help protect our planet for our children and future generations. We have a problem consuming most of the fossil energies right now, and our collaborative team is focused on refining our innovative way to clean up the mess."