Tuning acceptor energy level for efficient charge collection in copper-phthalocyanine-based organic solar cells

We compare organic donor/acceptor heterojunction photovoltaic devices based on copper phthalocyanine (CuPc) as the donor and [6,6]-phenyl C60 butyric acid methyl ester (PCBM) or buckminsterfullerene (C60) as the acceptor. The effect of the two acceptors on open-circuit voltage and short-circuit current density is studied. Improved interface properties, optimal energy level matching, and more balanced charge transport are believed to be the reasons for better performance of CuPc/PCBM heterojunction device, in terms of photocurrent and fill factor. The energy conversion efficiency of the devices under AM1.5G solar illumination at 130mW∕cm2 is improved to 1.18%, up from 0.74%.

[1]  C. Tang.  Two‐layer organic photovoltaic cell , 1986 .

[2]  Robert C. Haddon,et al.  C60 thin film transistors , 1995 .

[3]  Stephen R. Forrest,et al.  Asymmetric tandem organic photovoltaic cells with hybrid planar-mixed molecular heterojunctions , 2004 .

[4]  Mm Martijn Wienk,et al.  Electron Transport in a Methanofullerene , 2003 .

[5]  J. J. M. Vleggaar,et al.  Electron and hole transport in poly(p‐phenylene vinylene) devices , 1996 .

[6]  Christoph J. Brabec,et al.  Recombination and loss analysis in polythiophene based bulk heterojunction photodetectors , 2002 .

[7]  Klaus Meerholz,et al.  Influence of the anodic work function on the performance of organic solar cells. , 2002, Chemphyschem : a European journal of chemical physics and physical chemistry.

[8]  Valentin D. Mihailetchi,et al.  Bimolecular recombination in polymer/fullerene bulk heterojunction solar cells , 2006 .

[9]  Stephen R. Forrest,et al.  Very-high-efficiency double-heterostructure copper phthalocyanine/C60 photovoltaic cells , 2001 .

[10]  Gang Li,et al.  Investigation of annealing effects and film thickness dependence of polymer solar cells based on poly(3-hexylthiophene) , 2005 .

[11]  Christian Maria Anton Heller,et al.  Chemical potential pinning due to equilibrium electron transfer at metal/C60-doped polymer interfaces , 1997 .

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

[13]  Bernard Kippelen,et al.  Efficient thin-film organic solar cells based on pentacene/C60 heterojunctions , 2004 .

[14]  S. Forrest,et al.  Controlled growth of a molecular bulk heterojunction photovoltaic cell , 2004 .

[15]  Christoph J. Brabec,et al.  The influence of materials work function on the open circuit voltage of plastic solar cells , 2002 .

[16]  P. Sullivan,et al.  Influence of codeposition on the performance of CuPc-C60 heterojunction photovoltaic devices , 2004 .

[17]  C. Brabec,et al.  2.5% efficient organic plastic solar cells , 2001 .

[18]  D. Gebeyehu,et al.  Highly efficient p-i-n type organic photovoltaic devices , 2003 .