(174d) Combinatorial Organic Photovoltaic Microfluidic Device

The introduction of conjugated organic semiconductors to the field of photovoltaics has dramatically increased the number of materials available from which to construct solar cells. The theory of operation of organic solar cells based on the highest occupied molecular orbital (HOMO) of the electron donor and the lowest unoccupied molecular orbital (LUMO) of the electron acceptor provides a guideline for the synthesis of ideal n-type and p-type organic semiconductors which have the potential to achieve a conversion efficiency of over 10%. From an experimental standpoint, however, many material combinations go untested. Also, cell efficiency declarations are generally not very repeatable and are based on the best of a group of cells. This is mainly due to the fact that factors such as sealing and thickness control in these devices are not easily achievable. In this work, a microfluidic device has been designed to facilitate solar cell construction by making multiple n-type and p-type organic semiconductor combinations simultaneously. This design consists of multiple split chambers in which an n-type organic semiconductor is deposited in one half and then a p-type organic semiconductor is injected to fill the other half. This creates an interface between the two materials. Each cell has its own ITO coated polymer electrode and a metallic counter electrode which allow for measurements. A solar simulator is used to determine and compare the energy conversion efficiency of each cell. Dye sensitized solar cells can also be constructed and tested in a similar fashion, with electrolyte flowing through the microchannels to wet an electrode and dye combination in the chambers.