Research Areas
Organic Solar Cells
Photovoltaics is the process of converting sunlight directly into electricity using solar cells. Today it is a rapidly growing and increasingly important renewable alternative to conventional fossil fuel electricity generation, but compared to other electricity generating technologies, it is a relative newcomer, with the first practical photovoltaic devices demonstrated in the 1950s.
The fabrication of Organic Solar Cell is shown in the picture. In our lab, we synthesize polymers to incorporate them as an active layer in Organic Solar Cells. These polymers are characterized by various techniques.
Conjugated Polymers
Conjugated polymers are, at their very basic level, polymeric materials which have delocalized electron density along their backbone repeat structure. Most often this arises from structures containing alternating C-C σ- and π-bonds. Photovoltaics and OLEDs are one application where conjugated polymers are pushing towards practical applications in real world devices. The properties of conjugated polymer systems depend on their repeat structure, i.e. the atomistic arrangement of the monomer units within the chain, and the morphology of the chains, i.e how they are arranged and packed together.
Suitable materials for each potential application (light emitting diodes, solar cells, etc) can only be obtained then by controlling both the chemical repeat structure and the morphology of the polymers. Research efforts focus on designing molecular structures to optimize properties such as band-gap, mobility, and processability, as well as controlling the morphology of the chains for each specific application of conjugated polymers.
Organic Light Emitting Diodes
Conjugated polymers are a promising class of polymers for electroluminescence (EL) devices due to their ease of preparation, versatility and tunable band gap. An important part of our research is to study how the material properties affect devices performance, and to model device performance under various operation conditions which will provide insight into synthesis of new materials and optimization of device structure for further improvement in device performance.
TADF Materials
Thermally Activated Delayed Fluorescence (TADF) is a mechanism for enhancing the efficiency of Organic Light Emitting Diodes (OLEDs) by harvesting triplet excitons. In a TADF emitter the S1 and T1 levels are strongly coupled which allows ISC between the two levels. In addition the molecule is designed so that the energy difference between the S1 and T1 (ΔEST) is much smaller than in typical organic molecules, with a energy difference between the S1 and T1 for efficient TADF being less than 100 meV.
This small energy gap enables reverse intersystem crossing (RISC) to occur, where excitons in the T1 are converted to S1 in a thermally activated process. In our lab, we are trying to design, synthesize and characterize advanced TADF materials for light emitting applications.
Polymer Morphologies
Polymers are promising class for electroluminescence (EL) devices due to their ease of preparation, versatility and tunable band gap. An important part of our research is to study how the material properties affect devices performance, and to model device performance under various operation conditions which will provide insight into synthesis of new materials and optimization of device structure for further improvement in device performance.