Comparative study of aliphatic vs. aromatic substituted perylenediimide as electron transport layer material

Abstract

This work describes the study of solution processable perylene diimide (PDI) derivatives bearing aliphatic (PDI-EDAQ) and aromatic (PDI-PyQ) substituents at imide position as electron transport layer (ETL) material for organic solar cells. The PDI derivatives are easy to synthesize and most importantly soluble in methanol for processing feasibility. The materials have been characterized for their opto-electronic and electrochemical properties. The electron mobility was calculated by fabricating electron only devices and finally were tested PDI derivatives in inverted organic solar cell devices as ETL material using PTB7:PC71BM as active layer. Average power conversion efficiency was found to be 4.2% and 2.2% for PDI-EDAQ and PDI-PyQ based devices respectively. The champion device for PDI-EDA showed efficiency ~4.5%. The device properties have been compared with standard ZnO ETL devices and by theoretical simulation an explanation has been provided for observed behaviour.