Solar/Photovoltaic Materials
Introduction
Solar materials mainly include photovoltaic materials and solar thermal materials. In thermal energy storage, currently the main focus areas are cost reduction of storage material, cost reduction of operation and improvement in the efficiency of energy storage. Applications for the solar thermal materials can be classified as high, medium and low temperature areas. In high temperature side, inorganic materials like nitrate salts are the most used thermal energy storage materials, while on the lower and medium side organic materials like commercial paraffin are most used. Improving thermal conductivity of thermal energy storage materials is a major focus area. Cost effective manufacturing technologies for microencapsulated phase change materials and composite materials are being explored. Optimizing the thermophysical properties like melting point of thermal energy storage materials to suite a given requirement is also explored with techniques like eutectic mixtures and hydrocarbon chain length etc.
Types of Photovoltaic Materials
Photovoltaic materials, as the main components of solar cells, which help solar cells directly convert solar energy into electricity. Photovoltaic materials can be broadly classified into categories of organic, inorganic and organic-inorganic hybrid[1].
- Inorganic photovoltaic materials represented by Si, GaAs and CdTe etc. attract much attention because of their mature preparation technology, superior photovoltaic performance, high reliability and low cost, which greatly alleviate energy pressure. For instance, with highly stable and non-toxic, the silicon solar cell was the earliest developed and has been dominating the global PV market for decades.
- Organic photovoltaic materials are promising materials to support next-generation photovoltaic technologies, offering several advantages such as flexibility, low weight and translucency, which are compatible with large-scale solution processing and manufacturing, typically as polymers. Benefiting from the unique properties of organic photoactive materials, the design of novel organic photoactive materials, including electron donors and acceptors, is one of the most effective strategies to improve solar energy conversion efficiency. In the past decades, efforts have been made to introduce electron-absorbing halogens, such as fluorine, chlorine and bromine, into the conjugated building blocks to modulate the photoelectric properties and intermolecular aggregation of the materials and improve their conversion efficiency[2].
- Organic-inorganic photovoltaic hybrid materials are currently in the research and development stage, but they combine the advantages of both organic and inorganic materials, which definitely provide a possibility in the field of future solar cell to breakthrough conversion efficiency.
Application
In light of the growing shortage of fossil fuels and the increase of environmental pollution, it is becoming extremely difficult to ignore the development of clean energy[3]. In recent years, many solar materials with high absorption coefficient have emerged due to their low-cost and high power conversion efficiency potentials given that absorber layers with micron or even nanometer thickness can be fabricated making them suitable for thin-film solar cells on flexible substrates or as part of a tandem cell stack, thus becoming a competitive alternative or complimentary material to silicon solar cells. In conclusion, solar materials are presently regarded as a major component of the future new energy structure and have a very broad application prospect.
References
- Liu, Fangyang, et al. Emerging inorganic compound thin film photovoltaic materials: Progress, challenges and strategies. Materials Today, 2020, 41: 120-142.
- Polman, Albert, et al. Photovoltaic materials: Present efficiencies and future challenges. Science, 2016, 352.6283: aad4424.
- Yao, Huifeng, et al. Recent progress in chlorinated organic photovoltaic materials. Accounts of Chemical Research, 2020, 53.4: 822-832.