Technical / research - Page 13

Researchers from the University of Science and Technology of China and Hefei University of Technology have developed a proof-of-concept tandem solar cell tandem solar cell by using antimony selenide (Sb₂Se₃) for the bottom cell and a wide-bandgap organic-inorganic hybrid perovskite material for the top cell. The device reached a power conversion efficiency of more than 20%, which demonstrates that antimony selenide has a high potential for bottom-cell applications.

Antimony selenide (Sb₂Se₃) possesses a band gap of 1.05–1.2 eV and has been widely applied in single-junction solar cells. Based on its band gap, Sb₂Se₃ can also be used as the bottom cell absorber material in tandem solar cells. Sb₂Se₃-based solar cells also exhibit excellent stability with nontoxic compositional elements. In this recent work, the team demonstrated a perovskite/antimony selenide four-terminal tandem solar cell with a specially designed and fabricated transparent electrode for an optimized spectral response.

Researchers from the University of Victoria, University of British Columbia and Henan University recently used a cadmium iodide doping technique to stabilize the blade coating process in the manufacturing of solar cells based on formamidinium lead iodide (FAPbI₃) perovskite. The team built a cell showing a considerable increase in efficiency compared to an identical device without cadmium doping.

FAPbI₃ is one of the most promising perovskite materials for solar cell applications, as it offers a narrow energy bandgap and remarkable stability. However, there are still challenges to overcome considering the FAPbI₃ polymorphism issue and its hypersensitivity to fabrication conditions. The scientists hypothesized that introducing a homovalent Pb-site additive would be beneficial, and one such alternative is cadmium.

Researchers from Japan's Shibaura Institute of Technology and National Institute for Materials Science have developed a method to grow single-crystal perovskite hydrides, enabling accurate hydride conductivity measurements.

Perovskite hydrides, whose molecular structure contains hydrogen anions (H−), attract special attention because of their hydrogen-derived properties and many believe they can be useful for hydrogen storage technologies such as fuel cells and next-generation batteries, as well as energy-saving superconducting cables. However, measuring their intrinsic hydride-ion conductivity is difficult. In their recent study, the researchers addressed this issue using a novel laser deposition technique in an H-radical atmosphere. Using this approach, they grew thin-film single crystals of two different perovskite hydrides and characterized their hydride-ion conductivity. 

Researchers at the University of Toledo have designed a four-terminal (4T) tandem solar cell with a top device that uses a perovskite absorber with a tunable wide-bandgap and a bottom cell based on a commercially established narrow-bandgap absorber technology made of cadmium telluride (CdTe).

Perovskite-cadmium telluride tandem solar cells are relatively unexplored compared to other tandems. While the efficiency potential of CdTe-based tandems is lower than CIGS-based tandems due to the higher bandgap of the CdTe bottom cell, the broader commercial success of CdTe solar cells makes them interesting to investigate for thin-film tandem applications.

Small-molecule ionic liquids are frequently used as efficient bulk phase modifiers for perovskite materials. However, their inherent characteristics, such as high volatility and ion migration, pose challenges in addressing the stability issues associated with perovskite solar cells (PSCs). Recently, researchers at China's Northwestern Polytechnical University and CNPC Tubular Goods Research Institute designed improved poly ionic liquids (ILs) with multiple active sites as efficient additives for perovskite materials.

The team's recent work shows how additive engineering with a polymerized ionic liquid to the metal halide perovskite material can improve the solar cell's function, helping to pave the way for the adoption of perovskite solar cells.

Researchers from EPFL, CSEM and Empa have demonstrated a cell design combining additive and substrate engineering that yields consistently high power conversion efficiencies and discussed various design aspects that are important for reproducibility and performance. 

The team presented two key developments with a synergetic effect that boost the PCEs of tandem devices with front-side flat Si wafers—the use of 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPA) in the perovskite precursor ink that suppresses recombination near the perovskite/C60 interface and the use of SiO₂ nanoparticles under the perovskite film that suppress the enhanced number of pinholes and shunts introduced by pFBPA, while also allowing reliable use of Me-4PACz as a hole transport layer. 

Researchers at China's Shanghai University of Electric Power have used dibenzoylmethane (DBM) as a precursor additive introduced in order to regulate the crystallization of CsPbI₂Br perovskite while passivating its associated defects. 

Inorganic CsPbI₂Br perovskite solar cells (PSCs) have attracted massive interest but the tendency towards unruly crystallization and poor film quality of inorganic CsPbI₂Br perovskites are major factors limiting their performance improvement. In their recent work, the scientists used DBM additive engineering for efficient and stable carbon-based CsPbI₂Br PSCs.

A recent collaboration between the Hybrid³ team at Duke University (led by Professor Volker Blum) and SpringerMaterials has resulted in an insightful project called the Hybrid Perovskite Data Set, which enables researchers to compare and analyze different materials and optimize their properties for specific applications.

The huge number of variations of perovskite materials can make it challenging to find the most suitable material for a specific application. Now, researchers can use the data set to design new materials and experiment with new compositions, making the discovery of new materials more efficient and effective.

Researchers from India's Chiktara University have reported improved stability and performance of organic-inorganic perovskite solar cells by applying a strategy called bandgap grading.

The method is based on enabling the cell perovskite absorber to collect a wider range of light photons by modifying its thickness and characteristics. The team explains that its recent study demonstrates the effectiveness of both linear and parabolic bandgap grading strategies in optimizing light absorption and boosting performance, showing its potential. 

Researchers from the Hong Kong University of Science and Technology, Sun Yat-sen University and Nanjing University of Science and Technology have uniformly grown all-inorganic perovskite quantum wire arrays by filling high-density alumina nanopores on the surface of Al fibers with a dip-coating process. 

Fiber light-emitting diodes (Fi-LEDs), which can be used for wearable lighting and display devices, could be a key component for fiber/textile electronics. However, as a number of challenges exist with this technology, researchers are trying to address issues like on device fabrication with fiber-like substrates, as well as on device encapsulation.