Impact of Carrier Traps on Charge Transport in the Composites of Poly(3- Hexylthiophene) an Fullerene Derivative for Organic Photovoltaics
Keywords:organic solar cells, inverted layer sequence, efficiency, carrier trapping, mobility.
We have investigated impact of carrier trapping on charge transport in blends of poly(3-hexylthiophene) (P3HT) with
the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) that are important for the development of
organic Solar cells. The devices with quantum efficiency of 3.7 % fabricated in the inverted layer sequence were
analysed. We demonstrate that, though the fill factor of their Current-Voltage characteristics is as high as 68 %, carrier
trapping is effectively involved in the transport phenomena. The evaluated trapping state activation energy is about
0.18 eV and their density is up to (1020 ÷ 7×1021) cm–3. At such high densities these states presumably act as transport
states, limiting carrier mobility.
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