Solution processable luminescent fluorinated perylene derivatives showing high n-type mobility and columnar self-assembly

Abstract

Unsymmetrically substituted fluorinated perylenes and their corresponding all-alkyl derivatives were designed and synthesized using a microwave reactor. Perfluoro diester perylene (PEIF) was found to stabilize the columnar phase at high temperature, whereas the other fluoro derivative, perfluoro imide perylene (PBIF), exhibits crystalline properties. Both the alkyl derivatives, perylene ester imide (PEIH) and perylene bisimide (PBIH), are crystalline. All four molecules exhibit good solution processability and excellent thermal stability at high temperatures. All four derivatives are highly fluorescent with their relative quantum yield values reaching as high as ∼93% with respect to Rhodamine-6G. Compounds PEIF and PEIH in particular showed intense red emission in the solid state as well. The hydrophobic nature of these materials was also characterised by water contact angle measurements. A systematic investigation of SCLC devices revealed that PBIF exhibits exceptional out-of-plane bulk electron mobility of 1.3 × 10⁻² cm² V⁻¹ s⁻¹. This performance is attributed to its superior molecular packing, low surface roughness, optimal energy alignment, and high crystallinity. These findings underscore the critical role of structural order and interface engineering in the development of high-performance organic electron transport materials.