Near-infrared roll-off-free electroluminescence from highly stable diketopyrrolopyrrole light emitting diodes.
Organic light emitting diodes (OLEDs) operating in the near-infrared spectral region are gaining growing relevance for emerging photonic technologies, such as lab-on-chip platforms for medical diagnostics, flexible self-medicated pads for photodynamic therapy, night vision and plastic-based telecommunications. The achievement of efficient near-infrared electroluminescence from solution-processed OLEDs is, however, an open challenge due to the low photoluminescence efficiency of most narrow-energy-gap organic emitters. Diketopyrrolopyrrole-boron complexes are promising candidates to overcome this limitation as they feature extremely high photoluminescence quantum yield in the near-infrared region and high chemical stability. Here, by incorporating suitably functionalized diketopyrrolopyrrole derivatives emitting at ~760 nm in an active matrix of poly(9,9-dioctylfluorene-alt-benzothiadiazole) and without using complex light out-coupling or encapsulation strategies, we obtain all-solution-processed NIR-OLEDs with external quantum efficiency as high as 0.5%. Importantly, our test-bed devices show no efficiency roll-off even for high current densities and high operational stability, retaining over 50% of the initial radiant emittance for over 50 hours of continuous operation at 10 mA/cm2, which emphasizes the great applicative potential of the proposed strategy.
Dipartimento di Scienza dei Materiali Università degli Studi di Milano-Bicocca, via Cozzi 55, 20125, Milano, Italy.
Mauro
M
Sassi
Dipartimento di Scienza dei Materiali Università degli Studi di Milano-Bicocca, via Cozzi 55, 20125, Milano, Italy.
Nunzio
N
Buccheri
Dipartimento di Scienza dei Materiali Università degli Studi di Milano-Bicocca, via Cozzi 55, 20125, Milano, Italy.
Myles
M
Rooney
Istituto per lo Studio delle Macromolecole, Consiglio Nazionale delle Ricerche (ISMAC-CNR), Via Bassini 15, 20133, Milano, Italy.
Chiara
C
Botta
Dipartimento di Scienza dei Materiali Università degli Studi di Milano-Bicocca, via Cozzi 55, 20125, Milano, Italy.
Francesco
F
Bruni
Istituto per lo Studio delle Macromolecole, Consiglio Nazionale delle Ricerche (ISMAC-CNR), Via Bassini 15, 20133, Milano, Italy.
Umberto
U
Giovanella
Dipartimento di Scienza dei Materiali Università degli Studi di Milano-Bicocca, via Cozzi 55, 20125, Milano, Italy.
Sergio
S
Brovelli
Dipartimento di Scienza dei Materiali Università degli Studi di Milano-Bicocca, via Cozzi 55, 20125, Milano, Italy.
Luca
L
Beverina
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