Diffusion interface layer controlling the acceptor phase of bilayer near-infrared polymer phototransistors with ultrahigh photosensitivity

Abstract

The narrow bandgap of near-infrared (NIR) polymers is a major barrier to improving the performance of NIR phototransistors. The existing technique for overcoming this barrier is to construct a bilayer device (channel layer/bulk heterojunction (BHJ) layer). However, acceptor phases of the BHJ dissolve into the channel layer and are randomly distributed by the spin-coating method, resulting in turn-on voltages (Vo) and off-state dark currents remaining at a high level. In this work, a diffusion interface layer is formed between the channel layer and BHJ layer after treating the film transfer method (FTM)-based NIR phototransistors with solvent vapor annealing (SVA). The newly formed diffusion interface layer makes it possible to control the acceptor phase distribution. The performance of the FTM-based device improves after SVA. Vo decreases from 26 V to zero, and the dark currents decrease by one order of magnitude. The photosensitivity (Iph/Idark) increases from 22 to 1.7 × 107.

Controlling Electron/Hole Recombination in Near-Infrared Polymer Phototransistors through an Insulation Medium: A Pathway to Ultrahigh Photosensitivity

“…Figures a and S10a show that the dark current of the ternary system was 2–3 orders of magnitude lower than that of the binary system (@ V g = 0 V), indicating that PS doping could decrease the dark current of the NIR device. It should be noted that the dark current of NIR phototransistors is caused by the continuous injection of carriers from the electrode. ,, Hence, PS is assumed to isolate the donor/acceptor, and its insulation property increases the resistance to carrier injection from the electrode. Additionally, Figure b shows that the photocurrent of the ternary system was 1 order of magnitude higher than that of the binary system.…”

“…In our previous work, high-performance bilayer NIR phototransistors were successfully prepared by forming an acceptor diffusion interface instead of an immiscible interface to regulate electrons. The results showed that V o decreased from 26 V to zero, and the photosensitivity ( I ph / I dark ) increased from 22 to 1.7 × 10 7 …”

Aldol condensation-polymerized semiconducting polymers based on a BDOPV unit with near infrared absorption and better n-doped ability

“…N2200) always have a wide bandgap. [20][21][22][23] Therefore, it is of great significance to develop novel semiconducting polymers with new conjugated backbones to further narrow the bandgap. In addition to the rational design of novel semiconducting polymers, the doping effect can also efficiently tune the properties of semiconducting polymers, and broaden the absorption spectrum.…”

A nonbenzenoid acepleiadylene derivative with small band gap for near-infrared organic phototransistors

“…[2][3][4][5][6][7][8][9] In particular, NIR phototransistors can convert NIR light into electrical signals, realizing the detection of NIR light. [10][11][12][13][14][15][16][17] Traditional NIR phototransistors are mainly based on inorganic semiconductor materials, which nevertheless have the disadvantages of high cost and temperature sensitivity. 18 Benefiting from the characteristics of light weight, flexibility and solution processibility, organic semiconductors are ideal candidates for NIR light detection.…”