P3HT/n--Si Heterojunction Diodes and Photovoltaic Devices Investigated by I-V and C-V Measurements

Fumihiko HIROSE

IEICE TRANSACTIONS on Electronics   Vol.E94-C    No.12    pp.1838-1844
Publication Date: 2011/12/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E94.C.1838
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Organoelectronic Materials and Their Applications for Nanotechnology)
flexible electronics,  heterojunction,  Schottky diode,  poly(3-hexylthiophene),  

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Current density-voltage (J-V) and capacitance-voltage (C-V) characteristics of P3HT/n--silicon heterojunction diodes were investigated to clarify the carrier conduction mechanism at the organic/inorganic heterojunction. The J-V characteristics of the P3HT/n--Si junctions can be explained by a Schottky diode model with an interfacial layer. Diode parameters such as Schottky barrier height and ideality factor were estimated to be 0.78 eV and 3.2, respectively. The C-V analysis suggests that the depletion layer appears in the n--Si layer with a thickness of 1.2 µm from the junction with zero bias and the diffusion potential was estimated at 0.40 eV at the open-circuit condition. The present heterojunction allows a photovoltaic operation with power conversion efficiencies up to 0.38% with a simulated solar light exposure of 100 mW/cm2. The forward bias current was enhanced by coating the Si surface with a SiC layer, where the ideality factor was improved to be the level of 1.451.50.