TCTA:Ir(ppy)₃ Green Emissive Blends in Organic Light-Emitting Transistors (OLETs)

Abstract

Organic light-emitting transistors are photonic devices combining the function of an electrical switch with the capability of generating light under appropriate bias conditions. Achieving high-performance light-emitting transistors requires high-mobility organic semiconductors, optimized device structures, and highly efficient emissive layers. In this work, we studied the optoelectronic response of green blends (TCTA:Ir(ppy) 3 ) with varying doping concentrations in the limit of field-effect within a transistor device configuration. Increasing the dye concentration within the blend leads to a quenching of the photoluminescence signal; however, when implemented in a multilayer stack in a transistor, we observed an approximately 5-fold improvement in the light output for a 10% Ir(ppy) 3 doping blend. We analyzed our results in terms of balanced charge transport in the emissive layer, which, in the limit of field-effect (horizontal component), leads to an improved exciton formation and decay process. While the performances of our devices are yet to achieve the state-of-the-art diode counterpart, this work demonstrates that engineering the emissive layer is a promising approach to enhance the light emission in field-effect devices. This opens the way for a broader exploitation of organic light-emitting transistors as alternative photonic devices in several fields, ranging from display technology to flexible and wearable electronics.

Rational molecular design of phenanthroimidazole–azine derivatives for efficient non-doped blue organic light-emitting diodes with low-efficiency roll-off

“…Each EL spectrum matched well with its corresponding PL spectrum in thin films (Fig. 2(b)) without any additional peaks at low wavelengths from all buffer layers (NPB at 440 nm, 27 TCTA at ∼400 nm, 28 and TPBi at ∼380 nm), 29 indicating good balance of the charge transport in these devices. Moreover, upon varying the driving voltage from 7 V to 14 V, the shape and position of EL spectra of all devices were almost unchanged even at high voltages (Fig.…”

Hafnium Aluminate–Polymer Bilayer Dielectrics for Organic Light-Emitting Transistors (OLETs)

“…For a more detailed analysis of these emissive blends in terms of optical and optoelectronic properties in field-effect light-emitting transistors, we refer to one of our recent works. 57 Further, we also observed non-negligible hysteresis in our devices. Figure S8 summarizes the difference in drain−source current measured at fixed current between the forward and reverse sweeps for both PMMA-and ALD-OLET.…”

“…Additionally, the EQE values are expectedly underestimated, given that the measured light (bottom emission) is only a part of the total light generated in the device. For a more detailed analysis of these emissive blends in terms of optical and optoelectronic properties in field-effect light-emitting transistors, we refer to one of our recent works …”

“…In addition, controlling the interface morphology is highly desirable to enable an efficient conduction path within the semiconductor transport layers. More general considerations on the energetics of this multilayer OLET and materials therein, as well as on the full optoelectronic characterization of the used emissive blend, can be found in ref 57. Figure 3c shows an optical image of a representative substrate containing multiple (8) organic lightemitting transistors (top view).…”

Nonvolatile Memory Organic Light‐Emitting Transistors

“…Thus, the higher hole mobility in Fe-OLET was unfavorable to luminous efficiency. Second, in the case of higher hole concentration in the light-emitting layer, the charge-exciton and excitonexciton interactions may induce more excitons quenching, [45,46] giving rise to a lower probability of carrier recombination.…”