10:00 AM - 10:15 AM
▲ [18a-145-5] Study on Magnetoresistance (MR) of multilayer organic based on organic multilayer thin film field effect transistors
Keywords:magnetoresistance, singlet fission, organic field effect transistor
Singlet fission (SF) which transforms an excited singlet state into two excited triplet states has concentrated much attention because of its potential to increase the efficiency of organic solar cells. It has been reported pentacene is one of the materials which shows efficient singlet fission [1, 2].
In this work, we studied the magnetoresistance (MR) based on multilayer films composed of pentacene (PEN)/ perfluoro-pentacene (PFP) based field effect transistors under light illumination, as shown in figure 1. The MR was turned from positive to negative when the gate voltage (Vg) changed from positive to negative. There seem to be competing processes: (i) detraping of triplet exciton at the PEN/PFP interface and (ii) singlet fission in PEN layer. At negative Vg, the magnetoresistance shows a “W” shape negative MR curve with two peaks around ±50 mT as shown in figure 2. Under low magnetic field, the light illumination increases the singlet excitons or singlet excited states, which contributes to the photocurrent and to decrease the resistance of device (negative MR). Under high magnetic field, the singlet fission process increases the triplet excited states resulting in the decrease of photocurrent and lowering the negative MR. At positive Vg, the detraping of triplet excitons at PEN/PFP interface becomes the dominated process which causes in the positive MR curve as shown in figure 3.
In this work, we studied the magnetoresistance (MR) based on multilayer films composed of pentacene (PEN)/ perfluoro-pentacene (PFP) based field effect transistors under light illumination, as shown in figure 1. The MR was turned from positive to negative when the gate voltage (Vg) changed from positive to negative. There seem to be competing processes: (i) detraping of triplet exciton at the PEN/PFP interface and (ii) singlet fission in PEN layer. At negative Vg, the magnetoresistance shows a “W” shape negative MR curve with two peaks around ±50 mT as shown in figure 2. Under low magnetic field, the light illumination increases the singlet excitons or singlet excited states, which contributes to the photocurrent and to decrease the resistance of device (negative MR). Under high magnetic field, the singlet fission process increases the triplet excited states resulting in the decrease of photocurrent and lowering the negative MR. At positive Vg, the detraping of triplet excitons at PEN/PFP interface becomes the dominated process which causes in the positive MR curve as shown in figure 3.