Polymer solar cells usually consist of an electron- or hole-blocking layer on top of an indium tin oxide (ITO) conductive glass followed by electron donor and an electron acceptor (in the case of bulk heterojunction solar cells), a hole or electron blocking layer, and metal electrode on top.The nature and order of the blocking layers – as well as the nature of the metal electrode – depends on whether the cell follows a regular or an inverted device architecture.Finally, fractional kinetics and generalised diffusion equations are explored. (2011) Analytic solution of the fractional advection-diffusion equation for the time-of-flight experiment in a finite geometry.
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 nanometers.
Combined with the flexibility of organic molecules, organic solar cells are potentially cost-effective for photovoltaic applications. changing the length and functional group of polymers) can change the band gap, allowing for electronic tunability.
Compared to silicon-based devices, polymer solar cells are lightweight (which is important for small autonomous sensors), potentially disposable and inexpensive to fabricate (sometimes using printed electronics), flexible, customizable on the molecular level and potentially have less adverse environmental impact. The disadvantages of polymer solar cells are also serious: they offer about 1/3 of the efficiency of hard materials, and experience substantial photochemical degradation.
Polymer solar cells also have the potential to exhibit transparency, suggesting applications in windows, walls, flexible electronics, etc. A photovoltaic cell is a specialized semiconductor diode that converts light into direct current (DC) electricity.
Modelling of the steady-state photocurrent produced by a solar cell demonstrates the conditions under which non-geminate recombination may be avoided, and presents a design rule for avoiding non-geminate recombination. Philippa, Bronson, Stolterfoht, Martin, White, Ronald D., Velusamy, Marrapan, Burn, Paul L., Meredith, Paul, and Pivrikas, Almantas (2014) Molecular weight dependent bimolecular recombination in organic solar cells. Philippa, Bronson, Stolterfoht, Martin, Burn, Paul L., Juška, Gytis, Meredith, Paul, White, Ronald D., and Pivrikas, Almantas (2014) The impact of hot charge carrier mobility on photocurrent losses in polymer-based solar cells.
Experimental measurements on devices of varying thickness support the conclusion that the space-charge limited current is a fundamental threshold for high-efficiency photocurrent extraction. This work presents new insights into the measurement of charge transport, the underlying physics, as well as new approaches for modelling.Numeric simulation software using a drift-diffusion-recombination model is developed and applied to organic photovoltaic devices. PET – polyethylene terephthalate, ITO – indium tin oxide, PEDOT: PSS – poly(3,4-ethylenedioxythiophene), active layer (usually a polymer:fullerene blend), Al – aluminium.The main disadvantages associated with organic photovoltaic cells are low efficiency, low stability and low strength compared to inorganic photovoltaic cells such as silicon solar cells.A conjugated system is formed where carbon atoms covalently bond with alternating single and double bonds.These hydrocarbons' electrons pz orbitals delocalize and form a delocalized bonding π orbital with a π* antibonding orbital.It is argued instead that dispersive transport arises from the loss of carriers to trap states. Next, the techniques are extended to recombination measurements, where the recombination coefficient in a benchmark polymer:fullerene system is found to depend upon the polymer's molecular weight. These experiments demonstrate the absence of "hot carrier" relaxation effects on the timescales of charge transport in several organic photovoltaic polymer:fullerene blends. This is surprising because it has previously been argued that such relaxation is the cause of the deterimental dispersive transport that affects many organic semiconductor devices. (2014) Generalized phase-space kinetic and diffusion equations for classical and dispersive transport. Philippa, Bronson, Vijila, Chellappan, White, Ronald D., Sonar, Prashant, Burn, Paul L., Meredith, Paul, and Pivrikas, Almantas (2015) Time-independent charge carrier mobility in a model polymer: fullerene organic solar cell.