Performance Characteristics of Polymer Solar Cells with an Additive-Incorporated Active Layer

Abstract

Bulk heterojunction (BHJ) polymer solar cells, based on phase-separated blends of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C₆₁butyric acid methyl ester (PCBM) as an active layer, have been fabricated. During active layer forming process, single solvent, chlorobenzene or 1,2-dichlorobenzene, and a processing additive, 1,8-octanedithiol or 1,8-diiodooctane, were introduced. The effects of additives on the performance characteristics of polymer solar cells have been discussed based on the results from current density-voltage (J-V) measurements, UV-Vis absorption, X-ray diffraction spectra (XRD), and scanning probe microscope (SPM). At the presence of processing additives, the performance characteristics of polymer solar cells have been significantly improved and the peaks in UV-Vis absorption band of P3HT:PCBM films were apparently red-shifted, resulting in the enhancement of device efficiency due to the red-shifted absorption band. Furthermore, well ordered polycrystalline structure of P3HT molecules positively affected on the device efficiency in this work.

Keywords:

• Additive
• P3HT
• PCBM
• PEDOT:PSS
• polymer solar cells

Acknowledgment

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0003825) and the Brain Korea 21 project.