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Updated: Jan 29, 2026

Step-by-Step Guide for Harnessing Organic Light Emitting Diodes by Solution Processed Device Fabrication of a TADF Emitter
Published on: November 7, 2025
Realizing high-efficiency TADF from a low-performing cyanopyridine emitter via symmetric coupling
Ashish K Mazumdar1, Bhaskar Chelleng1, Svadha Devi1
1Materials Research Centre, Indian Institute of Science, Bengaluru, Karnataka-560012, India. rajamalli@iisc.ac.in.
Homo-coupling transforms low-performing cyanopyridine emitters into highly efficient Thermally Activated Delayed Fluorescence (TADF) materials. This method significantly enhances quantum efficiency by reducing energy loss pathways.
Area of Science:
- Organic electronics
- Materials science
- Photophysics
Background:
- Cyanopyridine-based emitters often exhibit low performance in organic light-emitting diodes (OLEDs).
- Thermally Activated Delayed Fluorescence (TADF) materials offer high efficiency but require careful molecular design.
Purpose of the Study:
- To develop a method for enhancing the efficiency of underperforming TADF emitters.
- To investigate the impact of symmetric homo-coupling on emitter performance.
Main Methods:
- Synthesis of a dual-core emitter (2tCz2Py2CN) via symmetric homo-coupling of a single-core emitter (tCzPyCN).
- Characterization of photophysical properties, including singlet-triplet energy gap (ΔEST) and photoluminescence quantum yield (PLQY).
- Evaluation of maximum external quantum efficiency (EQEmax) in OLED devices.
Main Results:
- Homo-coupling reduced ΔEST from 0.21 eV to 0.08 eV, creating a near-degenerate energy landscape.
- EQEmax increased significantly from 0.94% to 15.02%.
- Non-radiative triplet decay pathways were suppressed (kTnr = 0.11 × 105 s-1), and PLQY nearly doubled from 33.40% to 59.10%.
Conclusions:
- Symmetric homo-coupling is an effective strategy for converting low-performing emitters into highly efficient TADF materials.
- The reduction in ΔEST and suppression of non-radiative decay are key to the observed efficiency enhancement.
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