Confocal and near-field spectroscopic investigation of P3HT:PCBM organic blend film upon thermal annealing

The poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) organic films are widely employed as electronic donor and acceptor in the field of organic film solar cell because of their high photovoltaic conversion efficiency. A home-built parabolic mirror assisted confocal and apertureless near-field optical microscope was used to investigate the degradation behavior of the film and to distinguish the donor and acceptor domains both topographically and optically. Under ambient condition, the degradation rates are decreased in the sequence of pristine P3HT, blend P3HT:PCBM film and pristine PCBM. N2 protection dramatically slows down the film degradation rate. Using confocal spectroscopic mapping, we are able to distinguish the local distributions of P3HT and PCBM. Micrometer PCBM aggregates were observed due to the thermal annealing process. Our experimental methods show the possibility to investigate morphology and the photochemistry properties of the organic solar cell films with high spatial resolution.

[1]  Miller,et al.  Defect quenching of conjugated polymer luminescence. , 1994, Physical review letters.

[2]  Steven Holdcroft,et al.  INTERACTION OF OXYGEN WITH CONJUGATED POLYMERS : CHARGE TRANSFER COMPLEX FORMATION WITH POLY(3-ALKYLTHIOPHENES) , 1997 .

[3]  A. Pron,et al.  SERS spectra of poly(3‐hexylthiophene) in oxidized and unoxidized states , 1998 .

[4]  Marcus Sackrow,et al.  Imaging nanometre-sized hot spots on smooth au films with high-resolution tip-enhanced luminescence and Raman near-field optical microscopy. , 2008, Chemphyschem : a European journal of chemical physics and physical chemistry.

[5]  F. Krebs,et al.  Analysis of the failure mechanism for a stable organic photovoltaic during 10 000 h of testing , 2007 .

[6]  A. Meixner,et al.  Tighter focusing with a parabolic mirror. , 2008, Optics letters.

[7]  Xiong Gong,et al.  Thermally Stable, Efficient Polymer Solar Cells with Nanoscale Control of the Interpenetrating Network Morphology , 2005 .

[8]  A. Meixner,et al.  A high numerical aperture parabolic mirror as imaging device for confocal microscopy. , 2001, Optics express.

[9]  S. Holdcroft.  A photochemical study of poly(3-hexylthiophene) , 1991 .

[10]  Christoph J. Brabec,et al.  Stability and photodegradation mechanisms of conjugated polymer/fullerene plastic solar cells , 2000 .

[11]  F. Krebs,et al.  Stability/degradation of polymer solar cells , 2008 .

[12]  C. Brabec,et al.  Plastic Solar Cells , 2001 .

[13]  Vladimir Dyakonov,et al.  Influence of nanomorphology on the photovoltaic action of polymer–fullerene composites , 2004 .

[14]  W. Su,et al.  Study of the effect of annealing process on the performance of P3HT/PCBM photovoltaic devices using scanning-probe microscopy , 2009 .

[15]  Jenny Nelson,et al.  Morphology evolution via self-organization and lateral and vertical diffusion in polymer:fullerene solar cell blends. , 2008, Nature materials.

[16]  Chun-Wei Chen,et al.  Investigation of nanoscale morphological changes in organic photovoltaics during solvent vapor annealing , 2008 .

[17]  Christoph J. Brabec,et al.  Correlation Between Structural and Optical Properties of Composite Polymer/Fullerene Films for Organic Solar Cells , 2005 .

[18]  G. Lanzani,et al.  Oxygen-induced quenching of photoexcited states in polythiophene films , 2004 .

[19]  Niyazi Serdar Sariciftci,et al.  Effects of Postproduction Treatment on Plastic Solar Cells , 2003 .

[20]  Yang Yang,et al.  High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blends , 2005 .

[21]  Xiaoniu Yang,et al.  Scanning near-field and confocal Raman microscopic investigation of P3HT-PCBM systems for solar cell applications , 2006 .

[22]  Jean M. J. Fréchet,et al.  Polymer—Fullerene Composite Solar Cells. , 2008 .

[23]  Xiaoniu Yang,et al.  Nanoscale morphology of high-performance polymer solar cells. , 2005, Nano letters.