Optimal negative electrodes for poly(3-hexylthiophene): [6,6]-phenyl C61-butyric acid methyl ester bulk heterojunction photovoltaic devices

The role of the work function and interfacial chemistry on organic device performance was investigated by using a series of contact materials. The active layer was a standard blend of poly(3-hexylthiophene) and [6-6]-phenyl C61-butyric acid methyl ester. Over 100 devices were fabricated and measured to obtain good statistics. Ba∕Al and Ca∕Al electrodes performed best, with similar open-circuit voltages and power conversion efficiencies. Device stability studies showed devices with these two electrodes remained similar after six weeks with degradation of 11%–16% in net conversion efficiency observed. The incorporation of silver into the electrodes led to considerably more degradation than other electrode types.

[1]  Valentin D. Mihailetchi,et al.  Effect of metal electrodes on the performance of polymer : fullerene bulk heterojunction solar cells , 2004 .

[2]  H. Michaelson.  The work function of the elements and its periodicity , 1977 .

[3]  C. Brabec,et al.  Origin of the Open Circuit Voltage of Plastic Solar Cells , 2001 .

[4]  Christoph J. Brabec,et al.  Design Rules for Donors in Bulk‐Heterojunction Solar Cells—Towards 10 % Energy‐Conversion Efficiency , 2006 .

[5]  Y. Yoshida,et al.  Mg-doped C60 thin film as improved n-type organic semiconductor for a solar cell , 2004 .

[6]  Sean E. Shaheen,et al.  Inverted bulk-heterojunction organic photovoltaic device using a solution-derived ZnO underlayer , 2006 .

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

[8]  Valentin D. Mihailetchi,et al.  Device Physics of Polymer:Fullerene Bulk Heterojunction Solar Cells , 2007 .

[9]  Wilhelm Warta,et al.  Solar cell efficiency tables (version 29) , 2007 .

[10]  Stephen R. Forrest,et al.  Offset energies at organic semiconductor heterojunctions and their influence on the open-circuit voltage of thin-film solar cells , 2007 .

[11]  Valentin D. Mihailetchi,et al.  Charge Transport and Photocurrent Generation in Poly(3‐hexylthiophene): Methanofullerene Bulk‐Heterojunction Solar Cells , 2006 .

[12]  Michael D. McGehee,et al.  Conjugated Polymer Photovoltaic Cells , 2004 .

[13]  Ghassan E. Jabbour,et al.  Organic-Based Photovoltaics: Toward Low-Cost Power Generation , 2005 .