Highly photosensitive thin film transistors based on a composite of poly(3-hexylthiophene) and titania nanoparticles

Abstract

Organic phototransistors based on a composite of P3HT and TiO 2 nanoparticles have been fabricated, which show high photosensitivity, fast response, and stable performance under both visible and ultraviolet light illumination, and thus they are promising for applications as low cost photosensors. The transfer characteristic of each device exhibits a parallel shift to a positive gate voltage under light illumination, and the channel current increases up to three orders of magnitude in the subthreshold region. The shift in the threshold voltage of the device has a nonlinear relationship with light intensity, which can be attributed to the accumulation of electrons in the embedded TiO 2 nanoparticles. It has been found that the device is extremely sensitive to weak light due to an integration effect. The relationship between the threshold voltage change and the intensity of light illumination can be fitted with a power law. An analytical model has been developed to describe the photosensitive behavior of the devices. It is expected that such organic phototransistors can be developed for sensing different wavelengths based on different semiconducting polymers and semiconducting nanoparticles.

Enhancement of Hole Mobility of Poly(3‐hexylthiophene) Induced by Titania Nanorods in Composite Films

“…[ 1 ] Organic-inorganic nanocomposites are one type of advanced material for organic devices because of the expected synergy between the organic and inorganic components, which lead potentially to new physical properties of the composites and various applications in devices, including solar cells, [2][3][4][5][6] phototransistors, [7][8][9] memories, [ 10 ] and sensors. [ 11 ] The composites of a conjugated polymer such as poly(3-hexylthiophene) (P3HT) and inorganic nanoparticles, such as ZnO, TiO 2 , or CdSe, have been used in organic solar cells, and gratifying power conversion effi ciencies (PCEs) up to 3.8% have been obtained.…”

“…[ 8 , 9 ] A device with TiO 2 nanorods has been characterized under 370 nm UV light with different light intensities, as shown in Figure 3 d. It is worth noting that the current response of the device to light illumination is ∼ 10 times higher than that of the OTFT based on P3HT and TiO 2 nanoparticles reported in a previous paper. [8] The transfer curve shifts to a higher gate voltage horizontally with the increase of light intensity and the gate voltage change can be fi tted with the analytical model: [ 9 ] Δ V G = AI β , where A is a constant and β = 0.22. The shift of the transfer curve can be attributed to the accumulation of electrons in the embedded TiO 2 nanorods.…”

“…The shift of the transfer curve can be attributed to the accumulation of electrons in the embedded TiO 2 nanorods. [ 9 ] Under UV light illumination, excitons will be generated in the TiO 2 nanorods and dissociate at the TiO 2 /P3HT interfaces. Electrons will be trapped in the TiO 2 nanorods while holes will diffuse into the P3HT matrix.…”

“…[ 9 ] We fi nd that the nanoparticles not only infl uence the fi eld effect mobility of P3HT in transistors but also the bulk hole mobility characterized by measuring the space charge limited current (SCLC) of the composite fi lms. The J -V curves for the devices with the sandwich structure of Au/polymer composite/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/ indium tin oxide (ITO) glass have been measured ( Figure S5, Supporting Information).…”

A new strategy towards electroactive polymer–inorganic nanostructure composites. Silver nanoparticles inside polypyrrole matrix with pendant titanocene dichloride complexes

“…in catalysis and electrocatalysis [16,[19][20][21][22][23], sensors [24][25][26][27][28], micro and nanoelectronics [29], photovoltaics [30,31], batteries and capacitors [32,33], electrochromism [18].…”