Full electronic structure across a polymer heterojunction solar cell

被引:33
作者
Frisch, Johannes [1 ]
Schubert, Marcel [2 ]
Preis, Eduard [3 ]
Rabe, Juergen P. [1 ]
Neher, Dieter [2 ]
Scherf, Ullrich [3 ]
Koch, Norbert [1 ]
机构
[1] Univ Berlin, Inst Phys, D-12489 Berlin, Germany
[2] Univ Potsdam, Inst Phys & Astron, D-14476 Potsdam, Germany
[3] Univ Wuppertal, Fachbereich Makromol Chem C, D-42119 Wuppertal, Germany
关键词
OPEN-CIRCUIT VOLTAGE; DEVICE PHYSICS; EFFICIENCY; COPOLYMER; INTERFACES; BLENDS; STATES;
D O I
10.1039/c1jm14968g
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We correlate the morphology and energy level alignment of bilayer structures comprising the donor poly(3-hexylthiophene) (P3HT) and the acceptor polyfluorene copolymer poly(9,90dialklylfluorene-alt-4,7-bis(2,5-thiendiyl)-2,1,3-benzothiadiazole) (PFTBTT) with the performance of these bilayers in organic photovoltaic cells (OPVCs). The conducting polymer poly(ethylenedioxythiophene): poly (styrenesulfonate) (PEDT:PSS) was used as the bottom electrode and Ca as the top electrode. Ultraviolet photoelectron spectroscopy (UPS) revealed that notable interface dipoles occur at all interfaces across the OPVC structure, highlighting that vacuum level alignment cannot reliably be used to estimate the electronic properties for device design. Particularly the effective electrode work function values (after contact formation with the conjugated polymers) differ significantly from those of the pristine electrode materials. Chemical reactions between PEDT: PSS and P3HT on the one hand and Ca and PFTBTT on the other hand are identified as cause for the measured interface dipoles. The vacuum level shift between P3HT and PFTBTT is related to mutual energy level pinning at gap states. Annealing induced morphological changes at the P3HT/PFTBTT interface increased the efficiency of OPVCs, while the electronic structure was not affected by thermal treatment.
引用
收藏
页码:4418 / 4424
页数:7
相关论文
共 30 条
[1]  
[Anonymous], 1979, SURF INTERFACE ANAL, DOI DOI 10.1002/SIA.740010103
[2]   Device physics of polymer:fullerene bulk heterojunction solar cells [J].
Blom, Paul W. M. ;
Mihailetchi, Valentin D. ;
Koster, L. Jan Anton ;
Markov, Denis E. .
ADVANCED MATERIALS, 2007, 19 (12) :1551-1566
[3]   Energy-Level Alignment at Organic/Metal and Organic/Organic Interfaces [J].
Braun, Slawomir ;
Salaneck, William R. ;
Fahlman, Mats .
ADVANCED MATERIALS, 2009, 21 (14-15) :1450-1472
[4]   Polymer-Fullerene Bulk-Heterojunction Solar Cells [J].
Dennler, Gilles ;
Scharber, Markus C. ;
Brabec, Christoph J. .
ADVANCED MATERIALS, 2009, 21 (13) :1323-1338
[5]   Ultrathin polythiophene films on an intrinsically conducting polymer electrode: Charge transfer induced valence states and interface dipoles [J].
Frisch, J. ;
Vollmer, A. ;
Rabe, J. P. ;
Koch, N. .
ORGANIC ELECTRONICS, 2011, 12 (06) :916-922
[6]  
Fung M. K., J APPL PHYS, V94, P5764
[7]   Solar cell efficiency tables (Version 38) [J].
Green, Martin A. ;
Emery, Keith ;
Hishikawa, Yoshihiro ;
Warta, Wilhelm ;
Dunlop, Ewan D. .
PROGRESS IN PHOTOVOLTAICS, 2011, 19 (05) :565-572
[8]   Interface formation between metal and poly-dialkoxy-p-phenylene vinylene -: art. no. 165425 [J].
Janssen, FJJ ;
van IJzendoorn, LJ ;
van der Gon, AWD ;
de Voigt, MJA ;
Brongersma, HH .
PHYSICAL REVIEW B, 2004, 70 (16) :1-11
[9]   Effect of annealing on the electronic structure of poly(3-hexylthiophene) thin film [J].
Kanai, Kaname ;
Miyazaki, Takahiro ;
Suzuki, Hiroyuki ;
Inaba, Mina ;
Ouchi, Yukio ;
Seki, Kazuhiko .
PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 2010, 12 (01) :273-282
[10]   Spin-cast thin semiconducting polymer interlayer for improving device efficiency of polymer light-emitting diodes [J].
Kim, JS ;
Friend, RH ;
Grizzi, I ;
Burroughes, JH .
APPLIED PHYSICS LETTERS, 2005, 87 (02)