2D Conjugated Polyelectrolytes Possessing Identical Backbone with Active-Layer Polymer as Cathode Interlayer for...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Developing efficient cathode interlayer (CIL) materials is crucial for optimizing organic solar cell performance.
• Conjugated polyelectrolytes (CPEs) offer tunable electronic properties for interface engineering.

Purpose of the Study:

• To synthesize and evaluate a 2D conjugated polyelectrolyte, PBDTTh-TT-NBr, as a CIL for PTB7-Th-based solar cells.
• To investigate the structure-property relationship of CPEs for improved compatibility with active layer materials.

Main Methods:

• Synthesis of PBDTTh-TT-NBr with a 2D conjugated backbone and quaternary ammonium pendant.
• Fabrication and characterization of fullerene and non-fullerene solar cells using PBDTTh-TT-NBr as CIL.
• Comparative study with a non-2D CPE analogue (PBDT-TT-NBr).

Main Results:

• PBDTTh-TT-NBr exhibits enhanced compatibility with the PTB7-Th donor polymer due to structural similarity.
• The 2D CPE facilitates interface dipole formation, improving cathode modification.
• Devices with PBDTTh-TT-NBr as CIL showed superior performance in both fullerene and non-fullerene solar cells compared to devices with PBDT-TT-NBr.

Conclusions:

• Structural similarity between the CIL and the active layer donor polymer is a key factor for efficient electron transport and high device performance.
• PBDTTh-TT-NBr is a promising CIL material for PTB7-Th-based organic solar cells.
• Guidance is provided for selecting CIL materials with optimized structural complementarity to active layer components.