Effective absorption enhancement in small molecule organic solar cells using trapezoid gratings

• Published in: Chinese physics B Vol. 23; no. 3; pp. 673 - 677
• Main Author: 相春平 金玉 刘杰涛 许斌宗 汪卫敏 韦欣 宋国峰 徐云
• Format: Journal Article
• Language: English
• Published: 01.03.2014
• Subjects: Diffraction gratings; Gratings (spectra); Photovoltaic cells; Plasmons; Simulation; Solar cells; Surface chemistry; Trapezoids; 光吸收; 功率转换效率; 小分子; 有机太阳能电池; 有限差分时域法; 格栅; 梯形光栅; 表面等离子体
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/23/3/038803

We demonstrate that the optical absorption is enhanced in small molecule organic solar cells by using a trapezoid grating structure. The enhanced absorption is mainly attributed to both waveguide modes and surface plasmon modes, which is simulated by using finite-difference time-domain method. The simulated results show that the surface plasmon along the semitransparent metallic Ag anode is excited by introducing the periodical trapezoid gratings, which induce the increase of high intensity field in the donor layer. Meanwhile, the waveguide modes result in a high intensity field in acceptor layer. The increase of field improves the absorption of organic solar cells significantly, which is demonstrated by simulating the electrical properties. The simulated results also show that the short-circuit current is increased by 31% in an optimized device, which is supported by the experimental measurement. Experimental result shows that the power conversion efficiency of the grating sample is increased by 7.7%.