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Organic Solar Cell
An organic solar cell (OSC) or plastic solar cell is a type of photovoltaic that uses organic electronics, a branch of electronics that deals with conductive organic polymers or small organic molecules, for light absorption and charge transport to produce electricity from sunlight by the photovoltaic effect. Most organic photovoltaic cells are polymer solar cells. The molecules used in organic solar cells are solution-processable at high throughput and are cheap, resulting in low production costs to fabricate a large volume. Combined with the flexibility of organic molecules, organic solar cells are potentially cost-effective for photovoltaic applications. Molecular engineering (''e.g.,'' changing the length and functional group of polymers) can change the band gap, allowing for electronic tunability. The optical absorption coefficient of organic molecules is high, so a large amount of light can be absorbed with a small amount of materials, usually on the order of hundreds of na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Current
Direct current (DC) is one-directional electric current, flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor (material), conductor such as a wire, but can also flow through semiconductors, electrical insulation, insulators, or even through a vacuum as in electron beam, electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A archaism, term formerly used for this type of current was galvanic current. The abbreviations ''AC'' and ''DC'' are often used to mean simply ''alternating'' and ''direct'', as when they modify ''Electric current, current'' or ''voltage''. Direct current may be converted from an alternating current supply by use of a rectifier, which contains Electronics, electronic elements (usually) or electromechanical elements (historically) that allow current to flow only in one direction. Direct current may be converted into alt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valence And Conduction Bands
In solid-state physics, the valence band and conduction band are the bands closest to the Fermi level, and thus determine the electrical conductivity of the solid. In nonmetals, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of vacant electronic states. On a graph of the electronic band structure of a semiconducting material, the valence band is located below the Fermi level, while the conduction band is located above it. The distinction between the valence and conduction bands is meaningless in metals, because conduction occurs in one or more partially filled bands that take on the properties of both the valence and conduction bands. Band gap In semiconductors and insulators the two bands are separated by a band gap, while in conductors the bands overlap. A band gap is an energy range in a solid where no electron states can exist due to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HOMO/LUMO
In chemistry, HOMO and LUMO are types of molecular orbitals. The acronyms stand for ''highest occupied molecular orbital'' and ''lowest unoccupied molecular orbital'', respectively. HOMO and LUMO are sometimes collectively called the ''frontier orbitals'', such as in the frontier molecular orbital theory. Gap The energy difference between the HOMO and LUMO is ''the HOMO–LUMO gap''. Its size can be used to predict the strength and stability of transition metal complexes, as well as the colors they produce in solution. As a rule of thumb, the smaller a compound's HOMO–LUMO gap, the less stable the compound. Recent quantum‐chemical analyses of over 700 compounds demonstrated that terrestrial secondary metabolites exhibit HOMO–LUMO gaps on average about 2 eV narrower than organic molecules found in carbonaceous meteorites, and that combining gap width with hydrophilicity creates a robust discriminator between biotic and abiotic chemistries. This suggests that the HOMO–LU ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antibonding
In theoretical chemistry, an antibonding orbital is a type of molecular orbital that weakens the chemical bond between two atoms and helps to raise the energy of the molecule relative to the separated atoms. Such an orbital has one or more nodes in the bonding region between the nuclei. The density of the electrons in the orbital is concentrated outside the bonding region and acts to pull one nucleus away from the other and tends to cause mutual repulsion between the two atoms. This is in contrast to a bonding molecular orbital, which has a lower energy than that of the separate atoms, and is responsible for chemical bonds. Diatomic molecules Antibonding molecular orbitals (MOs) are normally ''higher'' in energy than bonding molecular orbitals. Bonding and antibonding orbitals form when atoms combine into molecules. If two hydrogen atoms are initially far apart, they have identical atomic orbitals. However, as the spacing between the two atoms becomes smaller, the electron w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delocalized Electron
In chemistry, delocalized electrons are electrons in a molecule, ion or solid metal that are not associated with a single atom or a covalent bond.IUPAC Gold Boo''delocalization''/ref> The term delocalization is general and can have slightly different meanings in different fields: * In organic chemistry, it refers to resonance in conjugated systems and aromatic compounds. * In solid-state physics, it refers to free electrons that facilitate electrical conduction. * In quantum chemistry, it refers to molecular orbital electrons that have extended over several adjacent atoms. Resonance In the simple aromatic ring of benzene, the delocalization of six π electrons over the C6 ring is often graphically indicated by a circle. The fact that the six C-C bonds are equidistant is one indication that the electrons are delocalized; if the structure were to have isolated double bonds alternating with discrete single bonds, the bond would likewise have alternating longer and short ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degenerate Orbitals
In quantum mechanics, an energy level is degenerate if it corresponds to two or more different measurable states of a quantum system. Conversely, two or more different states of a quantum mechanical system are said to be degenerate if they give the same value of energy upon measurement. The number of different states corresponding to a particular energy level is known as the ''degree of degeneracy'' (or simply the ''degeneracy'') of the level. It is represented mathematically by the Hamiltonian for the system having more than one linearly independent eigenstate with the same energy eigenvalue. When this is the case, energy alone is not enough to characterize what state the system is in, and other quantum numbers are needed to characterize the exact state when distinction is desired. In classical mechanics, this can be understood in terms of different possible trajectories corresponding to the same energy. Degeneracy plays a fundamental role in quantum statistical mechanics. For a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Covalent
A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full valence shell, corresponding to a stable electronic configuration. In organic chemistry, covalent bonding is much more common than ionic bonding. Covalent bonding also includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, bent bonds, three-center two-electron bonds and three-center four-electron bonds. The term "covalence" was introduced by Irving Langmuir in 1919, with Nevil Sidgwick using "co-valent link" in the 1920s. Merriam-Webster dates the specific phrase ''covalent bond'' to 1939, recognizing its first known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon
Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table. Carbon makes up about 0.025 percent of Earth's crust. Three Isotopes of carbon, isotopes occur naturally, carbon-12, C and carbon-13, C being stable, while carbon-14, C is a radionuclide, decaying with a half-life of 5,700 years. Carbon is one of the timeline of chemical element discoveries#Pre-modern and early modern discoveries, few elements known since antiquity. Carbon is the 15th abundance of elements in Earth's crust, most abundant element in the Earth's crust, and the abundance of the chemical elements, fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon's abundance, its unique diversity of organic compounds, and its unusual abi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjugated System
In physical organic chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases Chemical stability, stability. It is Resonance (chemistry), conventionally represented as having alternating single and multiple covalent bond, bonds. Lone pairs, radical (chemistry), radicals or carbenium ions may be part of the system, which may be Cyclic molecule, cyclic, acyclic, Linear molecular geometry, linear or mixed. The term "conjugated" was coined in 1899 by the German chemist Johannes Thiele (chemist), Johannes Thiele. Conjugation is the orbital overlap, overlap of one p-orbital with another across an adjacent Sigma bond, σ bond (in transition metals, d-orbitals can be involved). A conjugated system has a region of overlapping p-orbitals, bridging the interjacent locations that simple diagrams illustrate as not having a π bond. They allow a delocalization of pi el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photovoltaics
Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially used for electricity generation and as photosensors. A photovoltaic system employs solar modules, each comprising a number of solar cells, which generate electrical power. PV installations may be ground-mounted, rooftop-mounted, wall-mounted or floating. The mount may be fixed or use a solar tracker to follow the sun across the sky. Photovoltaic technology helps to mitigate climate change because it emits much less carbon dioxide than fossil fuels. Solar PV has specific advantages as an energy source: once installed, its operation does not generate any pollution or any greenhouse gas emissions; it shows scalability in respect of power needs and silicon has large availability in the Earth's crust, although other materials required ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymers
A polymer () is a substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeating subunits derived from one or more species of monomers. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals. Polymers are studied in the fields of polymer science (which includes polymer chemistry and polymer p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
