Acridine orange base as a dopant for n doping of C60 thin films

Abstract

We present a study on n doping of C60 thin films by acridine orange base [3,6-bis(dimethylamino)acridine(AOB)] combining conductivity, field effect, and Seebeck measurements. An increase of more than six orders of magnitude in conductivity is observed for a doping ratio of 6mol%, accompanied by a decrease in the activation energy from 0.64to0.15eV compared to the undoped C60. We observe a clear doping effect immediately after sample preparation, but also a further activation by annealing or illumination. The field effect and Seebeck measurements confirm n-type conduction of C60 thin films and show that deep donor states are formed in AOB-doped C60 thin films. A field effect mobility of 0.2cm2∕Vs is achieved for a doping level of 1.8mol%. Near Infrared (NIR) and Fourier transform infrared (FTIR) spectra demonstrate electron transfer from the dopant to the matrix: For C60 doped with AOB, C60− is present in NIR absorption and FTIR spectra. On the other hand, a peak corresponding to acridine orange [3,6-bis(dimethylamino)acridinium chloride (AOBH+)] is also observed in the FTIR spectrum of C60:AOB, where AOBH+ corresponds to AOB with one additional proton attached. Electrochemical data of AOB and AOBH+ in acetontrile suggest that the AOB radical cation is not stable, but is rapidly transformed into a compound with similar properties to AOBH+. Conductivities of C60 thin films doped with bis(ethylenedithio)-tetrathiafulvalene were also investigated to confirm that the doping effect of AOB in C60 does not result from a simple electron transfer from AOB to C60.

Role of band states and trap states in the electrical properties of organic semiconductors: Hopping versus mobility edge model

“…In analogy to inorganic semiconductors, the control of charge carrier concentration in organic semiconductors can be achieved by means of molecular doping [47][48][49][50][51][52] . Here, we apply both hopping and ME models to interpret the recent experimental data reported for n-doped C 60 films.…”

Ultralow Doping in Organic Semiconductors: Evidence of Trap Filling

“…Doping ratios used for devices and fundamental investigations usually range from 10 -2 to 10 -1 dopants per matrix molecule [18][19][20][21][22][23][24]. However, typical trap densities in disordered organic semiconductors are estimated to be in the range of 10 The doping studies were conducted on C 60 (Sigma Aldrich, 99.9% purity) and the n-dopant…”

Electrochemical Response of Acridine Orange in Bacterial Cell

“…Because the reduction of AO has been observed in more negative potential range around ¹1.0 V vs. SCE in the previous work. 24 It is well-known that acridine and similar structures give a characteristic electrochemical response depending on their structural changes, as shown in Fig. 4.…”

“…The AO +• immediately transforms into AOH + owing to its low structural stability. 24 Subsequently, the oxidation peak at 0.88 V was attributed to the oxidation of AOH + to the radical dication form (AOH 2+• ) in Fig. 4b.…”

“…4. [24][25][26][27] The oxidation peak at 0.72 V was attributed to the oxidization of neutral AO to the radical cation form (AO +• ) in Fig. 4a.…”