Polymer Films as Solar Cells

Recently, intense interest has been paid on doped poly(acetylene) because its film 68) showed markedly high conductivity on doping69 70 71 and the n- and p-type conductivities are depending on the dopants. The confirmation of p-n junction formation with the p- and n-type -fCH T, has roused great expectations to produce a polymer film solar cell.72a) 

The doping of with electron acceptors or donors increases the electrical 

The doped poly(acetylene) forms various junctions such as a) a p-n junction from p- and n- -f CH, b) a hetero-Schottky junction from the inorganic semiconductor and metalic -f CH-, and c) a heterojunction from the inorganic semiconductor and semiconducting The bandgaps of -(-CH (trans- 0.6 eV, cis- 0.9 eV) 

A solar cell was constructed from a p—fCH- film and a single crystalline n-Si wafer. The current-potential characteristic of the battery is shown in Fig. 20 73). A conversion efficiency of 4.3 % was obtained. The most sincere problem for poly-(acetylene) is its instability against air oxidation. If it could be solved, practical use of light weight and easily moldable solar cell from polymer films might be possible. 

Ferroelectric substances such as LiNb03 or BaTi03 were found to show anomalous photovoltaic effects (APV) of the order of 103-5 V83). A thin film of a ferroelectric polymer such as PVDF also was found to show APV effects84). Voc of 2.5 x 104 V and short circuit current (Isc) of the order of nA/cm2 were reported. Although the output is very small up to now1, it could be noticed as a specific photoeffect of a thin polymer film. 

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