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Silicon/organic semiconductor heterojunctions for solar cells
Author(s) -
Niesar Sabrina,
Dietmueller Roland,
Nesswetter Helmut,
Wiggers Hartmut,
Stutzmann Martin
Publication year - 2009
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200925322
Subject(s) - materials science , photocurrent , optoelectronics , heterojunction , silicon , photoconductivity , charge carrier , semiconductor , organic semiconductor , band gap , diode
Using current–voltage measurements, photocurrent spectroscopy, and light‐induced electron spin resonance (LESR), we have investigated hybrid solar cells consisting of composites of silicon nanocrystals (Si‐ncs) and poly‐3(hexylthiophene) (P3HT). For a more detailed understanding of the inorganic/organic interface, we have also studied the properties of crystalline silicon (c‐Si)/P3HT heterostructures. Current–voltage characteristics of Si‐ncs/P3HT blends show an open‐circuit voltage of up to 0.76 V. Photocurrent spectroscopy measurements give a strong indication that both, the Si‐ncs and P3HT, contribute to the photo‐induced current. Further, we directly demonstrate a light‐induced charge transfer between the Si‐ncs and P3HT via LESR. Current–voltage measurements of c‐Si/P3HT heterojunctions were performed under illumination with high power light emitting diodes (LEDs) of different wavelengths, which allow a selective excitation of charge carriers in P3HT, silicon, or both materials. We have observed a disadvantageous energy band alignment of the valence band of silicon and the highest occupied molecular orbital (HOMO) level of P3HT which favors the use of small particles with a larger band gap due to quantum confinement.