Photovoltage transients at fullerene-metal interfaces

Abstract

Photovoltage (PV) transients are studied in C60–Pb and C60–Au thin films. The morphology of the C60 layers is characterized by x-ray diffraction and atomic force microscopy, which evidence the formation of a nanocrystalline C60 layer on polycrystalline Pb and Au underlayers. In contrast to Au substrate, Pb crystallites with a (111) texture are predominantly formed. The signs of the PV signals developed at the C60–Pb and C60–Au interfaces are found to be opposite due to very different workfunction values of the two metals. The evolution of the PV rise and decay curves with increasing light illumination intensity is completely different at the C60–Pb and C60–Au interfaces. The rise for the C60–Pb interface speeds up considerably with the increase in intensity, which is markedly different from the behavior at C60–Au, which exhibits nearly unchanged curve shapes. The PV decay time for C60–Au is also only weakly affected by varying light intensity. In contrast, increasing the illumination intensity causes the decay curves for C60–Pb to become multiexponential profiles, developing fast initial decays. The results are discussed in terms of different charge redistribution properties of C60 molecules adsorbed on Pb(111) and Au interfaces. The observed transformation of the PV decay curves is explained by the presence of interface states and a subsequent interplay of the charge redistribution properties of C60 molecules adsorbed on Pb(111). The results can be applied to sandwich structures containing organic-metal interfaces to account correctly for the interfacial charge transfer dynamics.

Magnetic-Field-Stimulated Modification of Surface Charge and Defect Content in Silicon for Solar Energy Storage

“…Surface photovoltage (SPV) transients are measured in the capacitor arrangement [5], and details of our setup are given elsewhere [14,15].…”

Water‐based sonochemical cleaning in the manufacturing of high‐efficiency photovoltaic silicon wafers

“…The capacitor C t represents the shunt capacitance of the transducer. Then the pressure and displacement peak amplitudes are found to be ≈ 3.5 MPa and 13 μm at U 0 = 225 V. SPV transients are measured in the capacitor rrangement [5], and details of our setup are given elsewhere [6]. The scanning SPV apparatus based on the the AC-SPV technique [7] and utilizing a "flying spot" arrangement [8] is used for obtaining SPV decays and spatially-resolved SPV maps.…”

High-bandwidth, high-sampling-rate, low-noise, two-probe transient photovoltage measuring system

“…Hereafter, this coherent noise is referred to as system noise, and its origin is the focus of the present work. In this work, the traditional one-probe configuration for TPV measurement [14][15][16] (only one electrode was monitored by an oscilloscope, and the other was grounded) was promoted to the novel two-probe configuration, which allows for TPV measurements at up to 1.5 GHz (bandwidth) and 50 GS/s (sampling rate) without any degradation in the noise level. This two-probe measuring system is able to measure the TPV of either electrode of a typical sandwich-structured photoelectronic device (a thin photosensitive semiconductor layer sandwiched between two electrodes) independently, where one electrode is transparent to allow ambient illumination into the active layer independently.…”