Current Enhancement Phenomenon Caused by the Reversible Charge Trapping Effect Under Photoirradiation on Pentacene Field-Effect Transistors

Abstract

The fundamental aspect of the photoresponse feature was investigated in pentacene field-effect transistors with respect to the current enhancement phenomenon brought about by the balanced charge effect. The photoresponsivity behaviors attributed to the induced gate bias reveal that, resulting from their substantial trapping feature, photocarriers (electrons and holes) activated in pentacene solid contribute differently to the current drivability of the device. The reversible switching behavior under photoirradiation also clearly indicates that the current enhancement predominantly comes from the balanced charge effect, compensating for reversible trapped charges (electrons) in p-type devices, as well as excited majority carriers (holes) under photoirradiation.

Enhancement of ultraviolet light responsivity of a pentacene phototransistor by introducing photoactive molecules into a gate dielectric

“…This tendency is similar to the experimental results reported by other groups. 23,24,33) The maximum R (R max ) was obtained to be 0.12 A/W which is about one order of magnitude higher than that in previously reported UV pentacene phototransistors. 28,29) In addition, this value was obtained at the V G of ¹18 V which is the lowest V G among previous works.…”

“…The transistor performances are similar to those observed from previous pentacene phototransistors. [24][25][26][27][28][29][30] The photoelectrical characteristics of the phototransistor are shown in Fig. 3(a).…”

“…28,29) In addition, this value was obtained at the V G of ¹18 V which is the lowest V G among previous works. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]…”

“…Thus, the R depends on matching the absorption wavelength of the semiconducting material with the light wavelength. Although pentacene is widely used as a semiconducting layer of visible phototransistors, [15][16][17][18][19][20][21][22][23][24][25] the R of the pentacene phototransistor is low in the UV light region due to poor UV light absorption by pentacene. [26][27][28][29][30] In the present work, we demonstrate significant improvement of R in a pentacene phototransistor by introducing a photoactive gate dielectric layer composed of the layers of 6-[4A-(N,N-diphenylamino)phenyl]-3-ethoxycarbonylcoumarin (DPA-CM) doped into poly(methyl methacrylate) (PMMA) (PMMA:DPA-CM) and polystyrene.…”

Investigation of light programmable non‐volatile memory in an organic phototransistor

“…Nowadays, electronic devices using photoresponse features, such as photodetectors, phototransistors (PTs) or photovoltaic electronics, have become of great interest in thin film transistor (TFT) research, which might open up new fields of applications beyond the scope of TFT use as a conventional switching element . Among many types of alternatives for opto‐devices, organic electronics also show promising characteristics in that they have demonstrated high photosensitive behaviors such as a large photoresponsivity or photocurrent efficiency compared with those of inorganic devices .…”