Conference article

For production organic bulk heterojunction polymer solar cell one of the best materials is regioregular poly-3-hexylthiophene (P3HT); which is widely used as a donor molecule and a hole transporter; with soluble fullerene derivative (PCBM) as acceptor and electron transporter. The main drawback of this highly efficient blend is its limited spectral range; covering only 350-650 nm spectral interval. So main aim of present work was to extend the spectral range of the cell up to 850 nm by adding second bulk heterojunction layer of complementary absorption spectrum to P3HT:PCBM layer. For this purpose hydroxygallium phthalocyanine (GaOHPc) and PCBM blend was used as additional layer because GaOHPc has strong and wide intermolecular charge transfer (CT) absorption band around 830-850 nm. Thus novel organic bi-layer bulk heterojunction system (GaOHPc:PCBM/P3HT:PCBM) has been built by spin coating technique having high charge carrier photogeneration efficiency in 350 – 850 nm spectral range. It was found that thermal annealing in vacuum at 100C increases short circuit photocurrent external quantum efficiency (EQE) values more than 2 – 3 times; and these values reach more than 45% at P3HT absorption band (525 nm) and 25% at GaOHPc band (845 nm) for low light intensities (10¹² photon/(cm²*s)).

Full polymer film; heterojunction; organic solar cell