High-sensitivity organic phototransistors prepared by floating film transfer method

Abstract

In this report, the performance characteristics of organic phototransistors (OPTs) prepared by the floating film transfer method (FTM) and spin coating (SC) technique are compared. The FTM OPT shows a 2-order-higher photosensitivity under an electrically induced off-state as compared with the SC OPT. Furthermore, the FTM OPT shows improved gate voltage tunabilities of photosensitivity and responsivity as compared with the SC OPT. These observed results are explained on the basis of the improved thin film morphology of the active poly(3-hexylthiophene-2,5-diyl) (P3HT) layer in the FTM OPT, pointing towards the significance of thin film processing conditions in obtaining high-sensitivity OPTs.

Alignment of Organic Conjugated Molecules for High‐Performance Device Applications

“…Increased photocurrent resulted in a twofold enhancement in photosensitivity along parallel channel direction, reaching a maximum of 10 4 which was significantly higher than the previously reported polymer‐based OPTs, demonstrating the superiority of UFTM. [ 71i,74 ] Later, the same group further reported the anisotropic photosensitive characteristics of a low‐bandgap copolymer poly[2,6‐(4,4‐bis‐(2‐ethlhexyl)‐4H‐cycopenta[2,1‐b;3,4‐b′]dithiophene)‐alt‐4,7(2,1,3‐benzothiadiazole)] PCPDTBT under similar conditions. [ 71j ] The impressive device performance with maximum photosensitivity and photoresponsivity parallel to the PCPBTPT orientation direction was demonstrated.…”

Development of High‐Sensitivity Poly(2,7‐(9,9‐dioctylfluorene)‐alt‐5,5‐(4′,7′‐di‐2‐thienylbenzo [c][1,2,5]thiadiazole)) Thin‐Film‐Based Phototransistors by the Ribbon‐Floating Film Transfer Method

“…[1][2][3][4][5][6][7][8][9][10][11][12] Utilizing OFETs as light sensors is of interest as the active organic layer can be tailored to absorb photons of specific energy which when combined with the gain offered by the transistor can result in a highly sensitive device. [13][14][15][16][17][18][19] Recently, polymer-based organic photosensitive transistors (OPTs) have been demonstrated, opening the possibility to print these devices on flexible substrates, leading to flexible optoelectronic systems. [20][21][22] Previously, it was reported by Narayan and Kumar that poly(3-octylthiophene)-based OPTs demonstrated a photosensitivity (P) of 10 2 and a responsivity (R) of 1 A W À1 at a wavelength of 525 nm.…”

“…[24] A high photosensitivity of 10 4 was reported by Bhargava and Singh using poly(3-hexylthiophene)-based OPTs. [13] In recent past, various classes of low bandgap copolymers based on thiophene and benzothiadiazole donoracceptor moieties have been extensively investigated, as their absorption edge extends toward near-infrared region (NIR). [25][26][27] It has been established that orientation of polymer chains significantly influences performance of OFETs, due to their one dimensionality and extended π-conjugation facilitating molecular self-aggregation.…”

Freestanding Polymer Assembly Conductor by Contact-Free Annealing

“…7−14 Because the interchain charge transport is highly dependent on the π-orbital overlap between the adjacent polymer chains, it is critical to control the molecular orientation, ordering, microstructure, and morphology of conjugated polymer assembly. 15,16 Thus, obtaining highly ordered polymer materials by proper structural arrangement becomes critical for the practical device applications. Energy conversion devices using conjugated polymers have become increasingly feasible, while the performance variability is believed to be influenced by the molecular packing controlled electronic, optical, thermal, and structural properties.…”

“…Molecular ordering and geometrically confined crystalline polymer structures are regarded as a highly desirable strategy to simultaneously achieve high charge transport and mechanical robustness due to their unique electronic and structural properties from the suppressed defects, enhanced planarity, and electron delocalization. − The charge transport takes place not only along the backbone structure within the same polymer chains but also along the neighboring polymer chains. − Because the interchain charge transport is highly dependent on the π-orbital overlap between the adjacent polymer chains, it is critical to control the molecular orientation, ordering, microstructure, and morphology of conjugated polymer assembly. , Thus, obtaining highly ordered polymer materials by proper structural arrangement becomes critical for the practical device applications. Energy conversion devices using conjugated polymers have become increasingly feasible, while the performance variability is believed to be influenced by the molecular packing controlled electronic, optical, thermal, and structural properties.…”