PHOTOVOLTAIC AND PHOTOELECTROCHEMICAL PROPERTIES OF POLYDIACETYLENES

SEMICONDUCTOR POLYMERS HOLD PROMISE AS VERY INEXPENSIVE PHOTOCONVERSION MATERIALS WITH HIGH ELECTRONIC MOBILITIES COMPARED WITH MOLECULAR ORGANIC CRYSTALS. UNFORTUNATELY, THESE MATERIALS, EXEMPLIFIED BY POLYACETYLENE, CAN BE MADE ONLY IN A HIGHLY DISORDERED, POROUS MORPHOLOGY, SO THAT CHARGE TRANSPORT IS DICTATED BY EXTRINSIC FEATURES. POLYDIACETYLENES (PDAC) ARE EXCEPTIONAL, HOWEVER, BECAUSE THEY CAN BE MADE AS SINGLE CRYSTALS BY SOLID STATE POLYMERIZATION OF THE PARENT MONOMER. RECENT REPORTS OF CHEMICAL DOPING OF PDAC CRYSTALS INDICATE THAT THEY CAN BE MADE SUFFICIENTLY CONDUCTIVE TO EVALUATE AS PHOTOVOLTAIC MATERIALS. IT IS PLANNED IN PHASE I TO PREPARE SINGLE CRYSTALS OF A REPRESENTATIVE PDAC WITH A RANGE OF DOPING LEVELS (P-TYPE). SOLID STATE DIODES OF CONFIGURATION AU/P-PDAC/A1 (TRANSPARENT) WILL BE FABRICATED AND THEIR DARKAND PHOTOELECTRIC PROPERTIES EVALUATED AS A FUNCTION OF WAVELENGTH, INTENSITY, DOPING, AND CRYSTALLINE ORIENTATION. AU/P-PDAC ELECTRODES WILL ALSO BE INVESTIGATED AS PHOTOELECTRODES IN A NONREACTIVE, NONAQUEOUS ELECTROLYTE. THE RESULTS WILL BE INTERPRETED IN TERMS OF CURRENT THEORIESOF LIGHT-INDUCED CHARGE GENERATION AND SEPARATION. THE MECHANISM LIMITING PHOTOVOLTAIC ACTIVITY WILL BE USED TO DESIGN CHEMICAL MODIFICATIONS TO THE PDAC STRUCTURE, WHICH ARE LIKELY TO RESULT IN IMPROVED PERFORMANCE.