Acoustically Operated Excitonic Transistor Using Poly(3-hexylthiophene)

Abstract

An organic semiconductor, regioregular poly­(3-hexylthiophene) (rrP3HT), based excitonic transistor on a piezoelectric YZ lithium niobate substrate is reported for the first time. The propagating surface acoustic wave (SAW) field ionizes the excitons, stores the charge pair in the SAW modulated potential field in the semiconductor, and carries them forward. A long-range transport ∼4.7 mm at room temperature has been demonstrated. The electrical control of the exciton flux was achieved with SAW propagating through a dual metal–insulator–semiconductor (MIS) structure. The working of the device has been demonstrated using white and green light. A threshold voltage of −20.65 V was observed, and the working mechanism of the proposed device has been verified through numerical analysis using MATLAB. The potential use of the proposed device structure as an all optical device was verified electrically with additional electrode terminals at the output end.

Acoustic interactions with semiconductors: progression from inorganic to organic material system

“…Utilizing the effect of SAW on exciton movement, latterly work on an excitonic transistor using an organic semiconductor was proposed and demonstrated, marking itself as a potential fundamental work for acoustic all-optical devices. This work showed a long-range transport (∼4.7 mm) at room temperature and elaborated how a dual MIS structure can enable electrical control of the exciton flux to achieve transistor behavior [145].…”

“…In continuation of the above observations in the field of acousto-optics, the first report of an organic semiconductor-based excitonic transistor was very recently demonstrated in 2023 with the electrical control of the exciton flux being achieved through a dual MIS configuration [145]. The rrP3HT-based excitonic transistor showed charge transport across a long range distance of ∼4.7 mm at room temperature.…”

“…In the presence of V G , the capacitive effect at the MIS interface exponentially pulls and immobilizes the holes and electrons from the SAW field, causing an exponential reduction in the count of charges carried by the SAW out of the MIS configuration, and after the immobilized charges become proportionate to the capacitance at the applied V G , a part of the holes/electrons carried by the next half cycle of the SAW recombines with the immobilized negative/positive charges, causing a reduction in the count of charges carried out by the half cycle of the SAW. Once the threshold gate bias V th is reached, at which the maximum count of holes/electrons possible to be fetched in a single half cycle of the SAW recombines, and the charge profile in the following half cycle of the SAW immobilizes and recombines again, the device turns OFF [145]. The I −V characteristics of the excitonic transistor are shown in figure 26.…”

“…(b) Variation in the charge density in the rrP3HT-based MIS structure with varying gate voltage for white light as the input source, as analytically estimated via MATLAB. Reprinted with permission from[145]. Copyright (2023) American Chemical Society.…”