Tailoring Trap Density of States through Impedance Analysis for Flexible Organic Field‐Effect Transistors

Abstract

The selection of dielectric material impacts the dielectric/semiconductor (D/S) interface which plays a significant role in defining the device performance. Hence, investigation of the D/S interfacial defects and trap states is essential for improving the device performance and designing new semiconductor and dielectric materials for organic field effect transistors (OFET). Here, the trap density of states (DOS) at the interface is investigated by impedance spectroscopy (IS). OFETs are fabricated with three different dielectric combinations and the highest mobility is found to be 0.12 cm2 V−1 s−1. Detailed analysis of the semiconductor thin film and the D/S interface is performed by atomic force microscopy, photoluminescence, time‐resolved photoluminescence and is found consistent with the DOS analysis. This work validates that IS can be utilized as a prospective DOS analysis method for OFET applications. Finally, for evaluating the potential application of the device architecture toward developing flexible electronic circuit components, the device is fabricated on a flexible substrate and the mechanical stability is examined by subjecting the device to a strain of 2.5%. The device shows no significant degradation in operation, confirming its practical utility.

Tuning Polymer Semiconductor Morphology through Additive Engineering for a Stable Phototransistor

“…In the DIO-modified film, huge aggregations separated by large distances are observed in the AFM image (Figure b). This sort of morphology for the DIO modified PTB7-Th film has been previously obtained as well . Similar aggregation is seen in the FESEM image (Figure e) as well, however in FESEM, the domains can be visualized and an increase in the domain sizes compared with the control film is observed.…”

“…A ∼3-fold enhancement in mobility (0.22 cm 2 /V-s) was observed for the 1.5% v/v addition of DBrO compared to the control device (0.08 cm 2 /V-s). The mobility of the DBrO device has improved significantly from the previous PTB7-Th based OFET reports. ,,, However, at 2% of additive, the device repeatability and mobility were reduced (Figure d). This may be because of the residual solvent additive at higher additive concentrations, resulting in increased trap states …”

“…The device architecture of the OFET, the materials used as the semiconductor layer, and the solvent additives are presented in Figure a. A bilayer polymer dielectric system (PVA+PMMA) is adopted to achieve optimum accumulation of charges at the interface and reduced interfacial traps . The output characteristic graphs obtained for the three devices with optimum processing conditions are shown in Figure b–d.…”

Dual-Passivation Strategy for Improved Ambient Stability of Perovskite Solar Cells

“…The density of states (DOS) due to the trap-states was calculated from exponentially fitting the capacitance data obtained at various voltages (Figure d). Expectedly, DOS for the modified device was lower, and its distribution was narrower compared with control. , This ensured lower recombination and better charge transport in the PTSA2PS2 resulting in improved Voc and Jsc and hence a higher PCE than the device without any modification.…”

“…Expectedly, DOS for the modified device was lower, and its distribution was narrower compared with control. 35,48 This ensured lower recombination and better charge transport in the PTSA2PS2 resulting in improved Voc and Jsc and hence a higher PCE than the device without any modification.…”