Morphology-dependent performance of thin film organic solar cells

ABSTRACT

The photoactive film morphology of ternary molecules blend bulk heterojunction organic solar cell was investigated using various solvent additives. Two donor polymers namely poly(3-hexylthiophene) (P3HT) and thieno[3,4-b]thiophene/benzodithiophene (PTB7) at (1:1) stoichiometric ratio were employed together with (PC${}_{61}$BM) fullerene molecule in the preparation of the solar cells. The photoactive films were treated with either uni- or binary solvent additives to improve film morphology and the miscibility of the molecules in the medium. The significant improvement on the performances of the devices were recorded using binary solvent additives (∼1% vol.) with power conversion efficiency improvement as high as 4.1% compared to 2.9% measured from the films treated with single additive solvent. The correlation between solar cell performance and film morphology have been discussed in terms of optical, electrical and surface morphology of the active layers of solution processed organic solar cells.

KEYWORDS:

• Ternary molecules
• solvent additives
• optical properties
• surface morphology

PACS NUMBERS:

• 73.61.ph
• 73.61 Wp

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Genene Tessema Mola http://orcid.org/0000-0002-1510-4641

Additional information

Funding

This research work was supported by National Research Foundation (NRF), South Africa.