In an attempt to study the viability of organic solar cell technology, researchers from North Carolina State University and UNC-Chapel Hill have discovered that efficiency of energy transference within three-dimensional organic solar cells increases relatively when there is face-to-face alignment between the donor molecules and the acceptor molecules.
Exciton or the concentration of energy formed by excited particle upon absorbing by the material is the phenomenon upon which efficiency of organic solar cells is dependent. Within a solar cell, easier the exciton between the donor and acceptor molecules, higher will be the efficiency level and vice-versa.
Power conversion process
At the interface of the donor and acceptor molecules, the exciton is morphed into charges that move towards the electrodes and hence power is generated. This seems simple but at practical level, there are huddles to pass through, for example, particles can cluster into domains at both donor and acceptor layers, which might lead to inconsistency with respect to size, domain purity and could also affect the process involving the power conversion.
This is a very important aspect since the shapes of donor and acceptor molecules differ hence, their orientation with respect to each other is of great significance for an effective process to occur. At the same time, this complexity makes it very hard to calculate their structural characteristics as well.
Manipulating molecular orientation
Soft X-ray techniques were used by the team of researchers for studying the ideal structures of solar cells and the respective orientation of the molecules for giving out the most effective output. By working on different orientation on various polymers of solar cells, the experts were able to bring about the desired result by face-on alignment relatively.
As per the lead researcher, face-on alignment between the molecules in organic solar cells allows for effortless charge transfer and restrains the cluster formation, hence reducing the loss of charge.
Source: North Carolina State University