Organic photovoltaics have received extensive attention due to their excellent quality (the processability of the solution, adjustable electronic properties, low-temperature manufacturing and cheap and lightweight materials). Although several other photovoltaic technologies have higher efficiency, OPV still has advantages due to low toxicity, cost and environmental impact. So far, they have exceeded the certification efficiency of 13%, which is close to the efficiency value obtained by low-cost commercial silicon solar cells.
An OPV battery is a type of solar cell in which the absorber layer is based on organic semiconductors, usually polymers or small molecules. For organic materials to become conductive or semi-conductive, a high level of conjugation (alternating single and double bonds) is required. The conjugation of organic molecules causes the electrons associated with the double bond to become delocalized over the entire conjugation length, and these electrons have higher energy than other electrons in the molecule.
Fig 1. (a) Consecutive steps for photocurrent generation in a donor-acceptor heterojunction structure. (b) Schematic cross-section of planar donor–acceptor heterojunction. (c) Schematic cross-section of mixed or bulk heterojunction. (Cao W. R, et al. 2014)
However, in organic materials, these electrons do not occupy the valence band, but are part of the so-called "highest occupied molecular orbital" (HOMO). The first is called the lowest unoccupied molecular orbital (LUMO). There is an energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of OSC, which is usually called the bandgap of the material. As the conjugation increases, the bandgap will become small enough that visible light can excite electrons from HOMO to LUMO.
Compared with inorganic materials, the main advantage of OPV lies in its ability to be used in large-area and flexible solar cell modules as well as its lower cost and easier manufacturing than silicon-based materials. However, to catch up with the performance of silicon-based solar cells, both the donor and acceptor materials in OPV need to have a good extinction coefficient, high stability and good film morphology. Since the donor plays a vital role in absorbing solar photon flux, the donor material requires extensive light absorption to match the solar spectrum. Besides, another basic requirement of an ideal donor/acceptor is a large hole/electron mobility to maximize charge transport.
Fig 2. Schematic structure of organic photovoltaic devices with spontaneously-formed interdigitated structure. (Cao W. R, et al. 2014)
Leave a Reply
Related Products
You Might Like Also
Research Advancements in Carbon Nanotube Dispersion
Carbon nanotube dispersion has revolutionized various fields of science, including chemistry and materials science, due to their extraordinary mechanical, electrical, and thermal properties. Read More
![Magnetic Metal Complexes](https://d91ztqmtx7u1k.cloudfront.net/ClientContent/Images/Large/5e11089d-c95e-40f6-9fb5-cce96387b04b.jpg)
Magnetic Metal Complexes
Magnetic metal complexes are a kind of magnetic compounds formed by combining paramagnetic ions and diamagnetic ligands by means of spontaneous assembly and controlled assembly. Read More
Phosphorus Catalysts
Phosphorus catalysts are widely used in organic chemistry laboratories to convert acetic acid and formaldehyde into acrylic acid or used to catalyze hydrodesulfurization (HDS) and hydrodenitrogenation (HDN). Read More
Catalytic Hydrogenation
Catalytic hydrogenation is mainly used in the food industry, petrochemical industry and organic chemistry. Read More
Application of Zinc Gluconate as a dietary supplement
Zinc gluconate is a white to almost white solid that is soluble in water, practically insoluble in anhydrous ethanol and methylene chloride. Read More
![Ligands for Functional Metal Complexes](https://d91ztqmtx7u1k.cloudfront.net/ClientContent/Images/Large/becb31e6-245e-4dcb-9591-7b4390df5ceb.png)
Ligands for Functional Metal Complexes
Ligands for functional metal complexes usually have good coordination ability and chemical stability. Read More