Typical optical absorption spectra of ADT-TIPS-F and ADT-TES-F films. Inset shows molecular structures [ in ADT-TIPS-F, and in ADT-TES-F].
Schematics of the scanning photocurrent microscopy experiment.
(a) Transient photocurrents, normalized at their peak values, obtained in ADT-TIPS-F films on Au and Al electrodes under the same experimental conditions. Inset: long time-scale dynamics of the same transient photocurrents. Power-law fits are also shown. (b) Transient photoresponse peak amplitude as a function of applied voltage obtained in ADT-TIPS-F samples with Al or Au interdigitated electrodes.
(a) Dark current and (b) cw photocurrent obtained in ADT-TIPS-F films with Al and Au contacts in interdigitated geometry with gap. Power-law fits and in (a) and (b), respectively, are also shown.
Peak amplitudes of the transient photocurrent, normalized at their maximal values in the gap, at different positions of the localized beam spot obtained in ADT-TES-F and ADT-TIPS-F films on Au and Al electrodes, in coplanar electrode geometry with gap at 100 V and 150 V, respectively. Dashed lines correspond to the geometrical edges of the electrodes.
Cw photoresponse as a function of the beam position obtained in an ADT-TIPS-F film in coplanar electrode geometry with gap with (a) Al electrodes at 100 V and (b) Au electrodes at 30, 50, and 100 V. In (b), the curves are shifted along -axis for clarity. Ovals denote the “midgap” and “near-the-positively biased-electrode” regions, more data for which are shown in Fig. 7. Vertical dashed lines show positions of the edges of the electrodes.
Cw photoresponse obtained in an ADT-TIPS-F film in coplanar electrode geometry with gap with Au electrodes under (a) uniform illumination and (b) and (c) localized excitation of (b) midgap region and (c) of a region close to positive electrode (denoted by ovals in Fig. 6). Fits with a power-law function are also shown.
(a) Dark current density in an ADT-TES-F film on Au coplanar and ADT-TIPS-F film on Au interdigitated electrodes plotted as a function of applied voltage squared. Fits with Eqs. (1) and (2) are also shown. (b) Dark current density divided by voltage as a function of inverse voltage measured in ADT-TES-F and ADT-TIPS-F films on Al interdigitated electrodes. Fit with FN equation [Eq. (3)] is also included.
(a) Photocurrent density divided by applied voltage as a function of inverse voltage measured in an ADT-TES-F film on coplanar Al electrodes with cw photoexcitation at . Fit with FN equation [Eq. (3)] is also shown. (b) Slope from FN fits [Eq. (3)] to the cw photocurrent data (which reflects the product of the barrier height and effective width ), normalized at its value for the case of dark current (at ), as a function of light intensity in ADT-TES-F and ADT-TIPS-F films.
Schematics of the cw photoresponse under localized excitation of the region near (a) positively and (b) negatively biased electrodes. are electron (hole) currents flowing across the metal-organic interfaces at the electrodes 1 and 2, respectively.
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