An Improved Triple-Tandem Organic Solar Cell
- PDF / 295,032 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 96 Downloads / 320 Views
1212-S03-19
An Improved Triple-Tandem Organic Solar Cell D. W. Zhao,1 X. W. Sun,1 L. Ke,2 S. T. Tan3 1
Photonics Research Center (PhRC), School of Electrical and Electronic Engineering, Nanyang
Technological University, Nanyang Avenue, Singapore 639798, Singapore 2
Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology
and Research), 3 Research Link, Singapore 117602, Singapore 3
Institute of Microelectronics, A*STAR (Agency for Science, Technology and Research), 11
Science Park Road, Science Park II, Singapore 117685, Singapore ABSTRACT We present an efficient polymer-small molecule triple-tandem organic solar cell (OSC), consisting of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl(6,6)C61 (PCBM) bulk heterojunction as the first and second cells, and small molecules copper phthalocyanine (CuPc) and fullerene (C60) as the third cell on top. These sub-cells are connected by an intermediate layer of Al(1 nm)/MoO3(15 nm), which appears to be highly transparent, structurally smooth, and electrically functional. Compared to our previous all polymer tripletandem organic solar cells (2.03%), this polymer-small molecule triple-tandem organic solar cell achieves an improved power conversion efficiency of 2.18% with a short-circuit current density (Jsc) = 3.02 mA/cm2, open-circuit voltage (Voc) = 1.51 V, and fill factor (FF) = 47.7% under simulated solar irradiation of 100 mW/cm2 (AM1.5G), which can be attributed to the increased photocurrent generation in the third cell since the third cell has the complementary absorption with two bottom cells despite a slightly reduced Voc. INTRODUCTION Organic solar cells (OSCs) have attracted much attention in the past few years with their potential as a low-cost, easy-fabrication, and flexible alternative to conventional solar cells. The power conversion efficiency (PCE) of small molecule and polymer based OSCs has reached 5% or more [1-5]. The improvement of the efficiency can be realized by increasing the absorption efficiency, exciton diffusion/dissociation efficiency, charge transport efficiency, and charge collection efficiency. However, short exciton diffusion length and low charge carrier mobility in organic semiconductors limit the thickness of photoactive layer, resulting in less light absorption. Moreover, the open-circuit voltage (Voc) is only 0.60 V for a standard poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) single cell. Tandem structure, consisting of two or more cells with complementary absorptions stacked in series by optical and electrical connection, is believed to be an effective approach to enhance the light absorption and raise the Voc [6-13]. Shrotriya et al. reported double-tandem polymer cell with identical MEH-PPV/PCBM bulk heterojunction, exhibiting a Voc of 1.64 V [14]. MDMOPPV/PCBM bulk heterojunction was also used in such a double-tandem polymer cell and its corresponding Voc reached 1.34 V [15]. It has to be pointed out that issues such as incompletely
Data Loading...
