Organic polymer thin film phototransistors

Abstract

We have investigated the effects of illumination, both broadband and monochromatic, on the electrical performance of organic polymer thin-film transistors (OP-TFTs). In each case, providing the illumination is sufficiently absorbed by the organic polymer, the drain current of a device biased in the OFF-state is significantly increased. We have observed increases in the OFF-state drain current as large as several orders of magnitude depending on the intensity of the incident illumination. Whereas, the drain current of a device biased in the strong accumulation regime is relatively unaffected by the incident illumination. The illumination also serves to decrease the threshold voltage and increase the subthreshold slope, but has little effect on the field-effect mobility of the charge carriers. We explain these effects in terms of the photo-carrier generation in the channel region of the device due to the incident illumination. We have also studied how our OP-TFTs respond to the turn-on and turn-off of gate bias under illumination and to the turn-on and turn-off of illumination at certain gate biases.

Evolutionary parameter extraction for an organic TFT compact model including contact effects

“…Since the parameter set employed to generate the curves from is known, it can be used along with the fulfillment of f (x) (15) to verify the validity of the evolutionary procedure as a parameter extraction method in OTFTs. Experiments C and D, on the other hand, deal with the optimization and extraction of parameters of two real OTFT devices [17,73]. In Experiment C, a solution for the parameter set is also known [17], which can be compared against our results to test the effectiveness of our procedure.…”

“…A parameter extraction procedure is now applied to current-voltage characteristics of a [poly(9,9-dioctylfluoreneco-bithiophene)] (F8T2) based OTFT designed as phototransistor [73]. The structure used by these authors corresponds to an inverted, defined-gate, gate-planarized, coplanar TFT.…”

Charge-integrating organic heterojunction phototransistors for wide-dynamic-range image sensors

“…Examining the photocurrent at the drain electrode during integration provides insights into carrier dynamics not described by steady-state phototransistor behaviour 5,48 . Figure 4a shows the integrated photogenerated charge and the EQE of the rate of integrating charge, labelled 'instantaneous EQE', during light exposure for irradiances of 40 µW cm −2 and 323 µW cm −2 .…”

Semiconductor Nanomembrane-Based Light-Emitting and Photodetecting Devices

“…It has been reported that the metal oxide semiconductor field-effect transistors (MOSFETs) show outstanding characteristics in photosensitivity and responsivity [57]. Recently, we demonstrated a flexible phototransistor based on single crystalline silicon NMs.…”