Efficiency - Page 4

Researchers from Korea's Ulsan National Institute of Science and Technology (UNIST) have addressed critical challenges in perovskite solar cells (PSCs), significantly enhancing both their efficiency and stability. The team achieved precise control over ion arrangement and reduced structural irregularities by incorporating a bidirectional coordinator between the perovskite photoactive layer and the electron transport layer.

Image credit: UNIST

The research team introduced trifluoroacetate (TFA-) ions between the perovskite layer and the tin oxide substrate, which serves as the electron transport layer (ETL), to mitigate defects.

Researchers from Ming Chi University of Technology, National Taiwan University of Science and Technology and Chang Gung University have explored the effect of self-assembled monolayers (SAMs), readily deposited via spin-coating, on defect passivation in sol–gel NiOx for perovskite solar cells (PSCs).

The team explained that while mixed-halide PSCs are highly attractive for indoor light-harvesting applications (thanks to their tunable bandgap and low-cost fabrication), achieving efficient carrier transport and defect passivation at the critical nickel oxide (NiOx)/perovskite interface, particularly under low light conditions, remains a challenge. Self-assembled monolayers (SAMs) offer a promising solution by introducing a tailored interface that promotes perovskite growth, suppresses non-radiative recombination, and facilitates efficient carrier transport. 

Researchers at the Nova University of Lisbon, University of Aveiro and University of York have created an ultra-thin perovskite solar cell with a checkerboard tile pattern that shields the perovskite layer from UV degradation. The design includes a luminescent down-shifting encapsulant, which enhances UV photon conversion and boosts overall efficiency.

The team provided background for this work, stating that advanced light management techniques can enhance the sunlight absorption of perovskite solar cells (PSCs). When located at the front, they may act as a UV barrier, which is paramount for protecting the perovskite layer against UV-enabled degradation. Although it was recently shown that photonic structures such as Escher-like patterns could approach the theoretical Lambertian-limit of light trapping, it remains challenging to also implement UV protection properties for these diffractive structures while maintaining broadband absorption gains. 

Oxford PV has announced that it has started the commercialization of tandem solar technology with the first shipment to a U.S.-based customer.

The 72-cell panels, comprised of Oxford PV’s proprietary perovskite-on-silicon solar cells, can reportedly produce up to 20% more energy than a standard silicon panel. They will be used in a utility-scale installation, reducing the levelized cost of electricity (LCOE) and contributing to more efficient land use by generating more electricity from the same area.

The close collaboration between researchers at France's National Solar Energy Institute (INES) – a division of the French Alternative Energies and Atomic Energy Commission (CEA) - and 3SUN has reportedly yielded a certified efficiency record for a perovskite-on-silicon tandem photovoltaic cell measuring 9 cm² after shading correction.

The team explained that most of the efficiency records published internationally relate to a surface area of 1 cm². They said that the surface is a real challenge that they are addressing in their developments. This result marks a new stage in the development of PIN-type 2-terminal tandem cells. The progress is evident, with 26.5% in March 2023, then 27.1% in June 2023, 28.4% in December 2023, 28.7% last June and now 29.8%, for devices showing a Voc greater than 1900 mV.

Researchers from the Chinese Academy of Sciences, Beijing Institute of Technology and Shanghai Lettee Perovskite Optoelectronic Technology have addressed the issue of residual tensile strain - which impedes the improvement of efficiency and intrinsic stability of perovskite solar cells (PSCs) (resulting from the perovskite lattice distortion and different thermal expansion coefficients). To this end, they proposed a molecule-triggered strain regulation and interfacial passivation strategy to enhance the efficiency and stability (especially photostability) of PSCs.

Their strategy utilizes the [2 + 2] cycloaddition reaction of 6-bromocoumarin-3-carboxylic acid ethyl ester (BAEE), consuming the incident UV light to suppress the tensile strain evolution. 

Researchers from China's Huazhong University of Science and Technology, Wuhan University of Technology and Huaneng Clean Energy Research Institute have reported a surface reconstruction strategy utilizing a surface polishing agent, 1,4-butanediamine, together with a surface passivator, ethylenediammonium diiodide, to eliminate Sn-related defects and passivate organic cation and halide vacancy defects on the surface of Sn–Pb mixed perovskite films. 

The team explained that while all-perovskite tandem solar cells have shown great promise in breaking the Shockley–Queisser limit of single-junction solar cell, their efficiency is often hindered by the surface defects induced non-radiative recombination loss in Sn–Pb mixed narrow bandgap perovskite films. The strategy detailed in their recent work not only delivers high-quality Sn–Pb mixed perovskite films with a close-to-ideal stoichiometric ratio surface, but also minimizes the non-radiative energy loss at the perovskite/electron transport layer interface.

An international team of researchers, including ones from the University of Sydney, IEK-5 Photovoltaics at Forschungszentrum Jülich, Southern University of Science and Technology, UNSW and the University of Ljubljana, recently reported the use of a piperidinium bromide (PpBr) as an interlayer between C60 and perovskite. The interlayer was further optimized by introducing an additional oxygen atom on the opposite side of the NH²⁺. 

The tandem structure that the team used for demonstrations. Image credit: Advanced Energy Materials

This reportedly resulted in morpholinium bromide (MLBr) with increased dipole moment. Because of this, MLBr was highly effective in minimizing the energy band mismatch between perovskite and C60 layer for electron extraction while at the same time passivating defects. 

As the area of perovskite films and devices increases, their performance tends to deteriorate - which researchers from the Chinese Academy of Science (CAS), University of Science and Technology of China and Dalian University of Technology explain can be linked to defects that accumulate at the bottom surface without proper passivation. In an attempt to address this issue, the team introduced a unique molecule (1-(4-Fluorophenyl)−2-pyrrolidone, or FPP) as an additive in large-area blade-coating perovskite films. 

During the top-down crystallization process, the FPP molecule forms an intermediate phase with the perovskite components and subsequently self-deposits at the bottom surface. Consequently, the crystallization kinetics of the large-area thin films are regulated, and the bottom surface is effectively and uniformly passivated in one single-step processing. 

Sekisui Chemical and TERRA recently announced that they have commenced the first joint demonstration test in Japan to install film-type perovskite solar cells for agrivoltaics (solar sharing) at Sosa City, Chiba Prefecture on August 2, 2024.

Sekisui Chemical has created a 30 cm-wide roll-to-roll manufacturing process utilizing its original “sealing, film formation, materials and process technology,” and has reportedly confirmed 10 years equivalent of outdoor durability, which is critical to the development of film-type perovskite solar cells. Furthermore, this manufacturing process has been successfully used to produce film-type perovskite solar cells with a power generation efficiency of 15.0%. Development is being accelerated to further improve durability and power generation efficiency, as well as to establish manufacturing technology for 1 m-wide rolls.