Perovskite Solar - Page 70

Saule Technologies has unveiled its new PESL (Perovskite Electronic Shelf Label) technology - the world's first electronic price and advertising labels powered by perovskite photovoltaic cells. The devices enable wireless change of the messages displayed on it, and are said to have lifetimes of around 10 years.

Saule Tech has already released large-scale PSCs intended for building facades, PSC-powered blinds, and now, this new product from the IoT category ' an intelligent system for handling electronic labels, powered by a perovskite solar cell instead of the traditional battery.

Recent research has shown that the incorporation of graphene-related materials improves the performance and stability of perovskite solar cells. Graphene is hydrophobic, which can enhance several properties of perovskite solar cells. Firstly, it can enhance stability and the passivation of electron traps at the perovskite's crystalline domain interfaces. Graphene can also provide better energy level alignment, leading to more efficient devices.

In a recent study, Spain-based scientists used pristine graphene to improve the properties of MAPbI₃, a popular perovskite material. Pristine graphene was combined with the metal halide perovskite to form the active layer of the solar cells. By analyzing the resulting graphene/perovskite material, it was observed that an average efficiency value of 15% under high-stress conditions was achieved when the optimal amount of graphene was used.

Researchers from Rice University and collaborators from Purdue and Northwestern universities, U.S. Department of Energy national laboratories Los Alamos, Argonne and Brookhaven and the Institute of Electronics and Digital Technologies (INSA) in Rennes, France, have reached a new benchmark in the design of atomically thin solar cells made of semiconducting perovskites, boosting their efficiency while also focusing on their stability.

The lab of Aditya Mohite of Rice's George R. Brown School of Engineering discovered that sunlight itself contracts the space between atomic layers in 2D perovskites enough to improve the material's photovoltaic efficiency by up to 18%.

Three HZB teams, led by Prof. Christiane Becker, Prof. Bernd Stannowski and Prof. Steve Albrecht, have jointly managed to bring the efficiency of perovskite silicon tandem solar cells to a new record value of 29.80%. This result has been officially certified by Fraunhofer ISE CalLab and is documented in the NREL-charts.

The perovskite silicon tandem cell is based on two innovations: A nanotextured front side ( left) and a back side with dielectric reflector (right). © Alexandros Cruz /HZB

Several HZB groups have been working intensively since 2015 on both the perovskite semiconductors and silicon technologies and the combination of both into innovative tandem solar cells. In January 2020, HZB had achieved a record 29.15 % for a perovskite silicon tandem solar cell. Then, also in 2020, the company Oxford PV was able to announce a certified efficiency of 29.52%. Since then, the race for new records has been on. "An efficiency of 30% is like a psychological threshold for this fascinating new technology which could revolutionize the photovoltaic industry in the near future," explains Steve Albrecht, who is working on perovskite thin films at the HySPRINT lab at HZB. Bernd Stannowski, group leader for silicon technology, adds: "I would particularly emphasize the good cooperation between the different groups and institutes at HZB. This is how we managed to develop these new tandem solar cells entirely at HZB and once again get the world record."

A group of scientists, led by Prof. Yiqiang Zhan from Fudan University, has reported high-efficiency flexible perovskite solar cells (f-PSCs) by annealing a SnO₂ ETL in a rough vacuum at a low temperature (100 '), and peak efficiency reached 20.14%.

SnO₂ layers that have been prepared by this method have shown higher robustness and hydrophobicity in comparison with samples prepared in an air atmosphere and temperatures of 100 °C, leading to an improved ETL/perovskite interface connection and reducing defects in the SnO₂/perovskite interface. The appropriate density of oxygen vacancies on the surface during this treatment can be responsible for higher conductivity, which is beneficial for charge transfer.

Researchers from Professor Lioz Etgar's group at The Hebrew University of Jerusalem have recently studied the effects of electron transport layers (ETLs) and hole transport layer (ETLs) on the performance of inverted perovskite-based SC structures.

They focused on the inverted architecture, where the ETL and the HTL from the solar cell structure are eliminated. Three main architectures of were studied: a fully inverted structure, an ETL-free structure, and a HTL-free structure.

Scientists from Japan's Kishu Giken Kogyo and University of Hyogo, Switzerland's Solaronix and Germany's Fraunhofer ISE have examined the long-term stability of perovskite solar cells using layers of mesoporous carbon, building on previous work that showed the strong potential of this approach.

Schematics of reversible light-induced performance increase for m-CPSM. Image from study

This recent work demonstrated a light-soaking effect, which allowed them to fabricate cells that retained 92% of their initial performance after 3,000 hours in damp heat conditions – which the researchers say is equivalent to 20 years in the field.

A project called NanoQI, funded by the European Union with Horizon 2020 funds, aims to develop an industry-ready, real-time and in-line capable method for characterizing and imaging nano-dimensions of (thin film) nanomaterials in the critical range of 1 to 300 nm on large sample surfaces of more than 500 × 500 mm². The project involves a consortium of eight companies and organizations from five European countries and was initiated on March 1, 2020. The project's mid-term was in September 2021.

HSI hardware integration and algorithms for automatic quality assessment using HSI, based on XRR/XRD- ground-truth data. (Image: Fraunhofer IWS)

NanoQI combines for the first time X-ray reflectometry (XRR) and X-ray diffraction analysis (XRD) as well as broadband hyperspectral imaging (HSI) into a fast, real-time method for quality control in thin film processing that can be directly integrated into the coating equipment. This combination enables equipment operators to access application-relevant properties such as the thickness of individual layers in a coating system, the solid state structure or even derived functional properties ' such as water vapor permeability ' while the coating is still in progress.

In October 2021, The Perovskite-Info team met Cyprus University of Technology's (CUT) Professor Stelios Choulis, who kindly agreed to show us around his workspace and labs and update us on his team's ongoing work.

Choulis, Professor of Material Science and Engineering at the Cyprus University of Technology, is also the founder and head of the Molecular Electronics and Photonics (MEP) Research Unit. With work in UK, Germany and the Silicon Valley (USA) under his belt, Choulis is a highly skilled and experienced researcher in the fields of both photovoltaics and OLEDs. He also participated and led several large-scale research programs (ERC-Consolidator Grant European Horizon project, SME-EU FP7, RIF and RPF-Cyprus, BMBF-Germany, DOE-USA).

An international team of researchers recently tested a new way of passivating defects in perovskite solar cells. Using a tailored arrangement of atoms, the team managed to overcome challenges related to the formation of a two-dimensional perovskite layer on top of the active cell material, and reach 21.4% conversion efficiency for a 26cm² active area, which is said to be a record for a perovskite device of this size.

Passivation layers, deposited on top of the perovskite material, play an essential role in reducing material defects and unwanted reactions within the material, to improve both performance and stability. One strategy that has been found effective is the use of alkylammonium halides. In many cases these form an additional two-dimensional perovskite layer on top of the perovskite, which can improve device stability but also negatively affect performance.