Morphology Related Photodegradation of Low‐Band‐Gap Polymer Blends

The morphology related photodegradation of low band‐gap polymer blends is investigated using optical microscopy and scanning probe microscopy. Poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene)‐alt‐4,7(2,1,3‐benzothiadiazole)] (C‐PCPDTBT):[6,6]‐phenyl C61‐butyric acid methyl ester (PCBM) blend films without and with ODT, as well as poly[(4,40‐bis(2‐ethylhexyl)dithieno[3,2‐b:20,30‐d]silole)‐2,6‐diylalt‐(2,1,3‐benzothiadiazole)‐4,7‐diyl] (Si‐PCPDTBT):PCBM blend films exposed to a focused 632.8 nm laser under ambient condition with and without inert gas protection are studied. The photodegradation of the polymer starts in the vicinity of the PCBM molecules (first sphere degradation), which effectively blocks the electron transfer processes. Stern‐Volmer type kinetics are observed in the C‐PCPDTBT:PCBM blend with ODT, which indicates that only a small number of photo‐oxidized monomer units act as quenchers of the C‐PCPDTBT polymer luminescence. Furthermore, in addition to the permanent damage of the polymer molecules, as witnessed from their Raman intensity decrease, the polymer photoluminescence demonstrates partial reversible recovery when inert gas protection is resumed, indicating the involvement of temporary polymer/O2‐charge transfer complexes in the photodegradation process.

[1]  G. Lanzani,et al.  The critical role of interfacial dynamics in the stability of organic photovoltaic devices. , 2014, Physical chemistry chemical physics : PCCP.

[2]  Hans-Joachim Egelhaaf,et al.  The Effect of PCBM Dimerization on the Performance of Bulk Heterojunction Solar Cells , 2014 .

[3]  M. Toney,et al.  A general relationship between disorder, aggregation and charge transport in conjugated polymers. , 2013, Nature materials.

[4]  Zhenggang Huang,et al.  Performance enhancement of fullerene-based solar cells by light processing , 2013, Nature Communications.

[5]  W. Tsoi,et al.  In-situ monitoring of molecular vibrations of two organic semiconductors in photovoltaic blends and their impact on thin film morphology , 2013 .

[6]  John R. Tumbleston,et al.  The Importance of Fullerene Percolation in the Mixed Regions of Polymer–Fullerene Bulk Heterojunction Solar Cells , 2013 .

[7]  John R. Tumbleston,et al.  Absolute Measurement of Domain Composition and Nanoscale Size Distribution Explains Performance in PTB7:PC71BM Solar Cells , 2013 .

[8]  René A. J. Janssen,et al.  Effect of PCBM on the Photodegradation Kinetics of Polymers for Organic Photovoltaics , 2012 .

[9]  Isaac Kauvar,et al.  The Role of Electron Affinity in Determining Whether Fullerenes Catalyze or Inhibit Photooxidation of Polymers for Solar Cells , 2012 .

[10]  M. Gordon,et al.  Raman and low temperature photoluminescence spectroscopy of polymer disorder in bulk heterojunction solar cell films , 2012 .

[11]  T. P. Russell,et al.  Multi‐Length‐Scale Morphologies in PCPDTBT/PCBM Bulk‐Heterojunction Solar Cells , 2012 .

[12]  Mauro Morana,et al.  Exciton diffusion length in narrow bandgap polymers , 2012 .

[13]  H. Egelhaaf,et al.  Probing the nanoscale phase separation and photophysics properties of low-bandgap polymer:fullerene blend film by near-field spectroscopic mapping. , 2011, Small.

[14]  Hans-Joachim Egelhaaf,et al.  Low‐Temperature Behaviour of Charge Transfer Excitons in Narrow‐Bandgap Polymer‐Based Bulk Heterojunctions , 2011 .

[15]  D. Bradley,et al.  The nature of in-plane skeleton Raman modes of P3HT and their correlation to the degree of molecular order in P3HT:PCBM blend thin films. , 2011, Journal of the American Chemical Society.

[16]  Hans-Joachim Egelhaaf,et al.  Photodegradation of P3HT−A Systematic Study of Environmental Factors , 2011 .

[17]  C. Brabec,et al.  Nanomorphology and Charge Generation in Bulk Heterojunctions Based on Low‐Bandgap Dithiophene Polymers with Different Bridging Atoms , 2010 .

[18]  C. Brabec,et al.  High‐Resolution Spectroscopic Mapping of the Chemical Contrast from Nanometer Domains in P3HT:PCBM Organic Blend Films for Solar‐Cell Applications , 2010 .

[19]  Zhengguo Zhu,et al.  Influence of the Bridging Atom on the Performance of a Low‐Bandgap Bulk Heterojunction Solar Cell , 2010, Advanced materials.

[20]  Christoph J. Brabec,et al.  Parabolic mirror‐assisted tip‐enhanced spectroscopic imaging for non‐transparent materials , 2009 .

[21]  Akihiro Furube,et al.  Estimate of singlet diffusion lengths in PCBM films by time-resolved emission studies , 2009 .

[22]  J. Grey,et al.  Resonance chemical imaging of polythiophene/fullerene photovoltaic thin films: mapping morphology-dependent aggregated and unaggregated C=C Species. , 2009, Journal of the American Chemical Society.

[23]  Andrés J. García,et al.  Three-Dimensional Nanoscale Organization of Highly Efficient Low Band-Gap Conjugated Polymer Bulk Heterojunction Solar Cells , 2009 .

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

[25]  G. Bazan,et al.  Insight into the Raman shifts and optical absorption changes upon annealing polymer/fullerene solar cells , 2008 .

[26]  Christoph J. Brabec,et al.  Bipolar Charge Transport in PCPDTBT‐PCBM Bulk‐Heterojunctions for Photovoltaic Applications , 2008 .

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

[28]  Jin Young Kim,et al.  Processing additives for improved efficiency from bulk heterojunction solar cells. , 2008, Journal of the American Chemical Society.

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

[30]  Donal D. C. Bradley,et al.  A photophysical study of PCBM thin films , 2007 .

[31]  Daniel Moses,et al.  Ultrafast Electron Transfer and Decay Dynamics in a Small Band Gap Bulk Heterojunction Material , 2007 .

[32]  N. E. Coates,et al.  Efficient Tandem Polymer Solar Cells Fabricated by All-Solution Processing , 2007, Science.

[33]  A J Heeger,et al.  Efficiency enhancement in low-bandgap polymer solar cells by processing with alkane dithiols. , 2007, Nature materials.

[34]  J. Gardette,et al.  Photo- and thermal degradation of MDMO-PPV:PCBM blends , 2007 .

[35]  Christoph J. Brabec,et al.  High Photovoltaic Performance of a Low‐Bandgap Polymer , 2006 .

[36]  Dieter Meissner,et al.  Nanoscale Morphology of Conjugated Polymer/Fullerene‐Based Bulk‐ Heterojunction Solar Cells , 2004 .

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

[38]  Christoph J. Brabec,et al.  A low-bandgap semiconducting polymer for photovoltaic devices and infrared emitting diodes , 2002 .

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

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