Characterization of polymer:fullerene solar cells by low-frequency noise spectroscopy

Abstract

A detailed electric noise investigation of polymer:fullerene solar cells, at 300 K under dark conditions, is reported. The experimental noise results are interpreted in terms of a model taking into account the device capacitance and recombination resistance. Relevant parameters of the solar cells can be computed through fluctuation spectroscopy, and the results have been compared with those obtained by alternative techniques. After a thermal treatment at 340 K, a modification of the voltage-spectral traces has been observed and related to a strong cell resistance reduction

Investigation of the solvent influence on polymer–fullerene solar cells by low frequency noise spectroscopy

“…The AC electrical impedance at low frequency of the polymerfullerene solar cell can be modeled as a parallel connection between a random fluctuation of the differential resistance, R x (t), and an equivalent capacitance, C x [9]. The voltage spectral noise generated by the device is related to the mean value of R x (t), identified with the recombination resistance R rec = (dV F /dI DC ).…”

“…It is well known that the morphology of the active layer is very sensitive to the processing conditions, and strongly depends on the choice of solvent [6,7] and possible additives [8]. To reveal the morphological modifications in the active layer, low-frequency noise spectroscopy has recently been used [9,10]. This experimental nondestructive technique has proved to be a powerful tool for the analysis of electric transport and recombination phenomena in solar cell devices, and very useful for the extraction of relevant parameters, such as density of states (DOS) and electron lifetime.…”

Probing Temperature-Dependent Recombination Kinetics in Polymer:Fullerene Solar Cells by Electric Noise Spectroscopy

“…The second one is the thermal noise , which characterizes the high-frequency region of the spectrum and depends on temperature fluctuations of the charge carriers interacting with the polymeric chains [27]. By modeling the electronic behavior of the cells with a simple RC circuit formed by the recombination resistance and the chemical capacitance of the active layer [32,33], it is possible to express as [25]:…”

“…By modeling the electronic behavior of the cells with a simple RC circuit formed by the recombination resistance R rec and the chemical capacitance C µ of the active layer [32,33], it is possible to express S V . as [25]:…”

“…Moreover, noise investigation has been used to characterize defect states and phase-transitions in crystalline silicon-based and perovskite-based solar cells [22][23][24]. Additionally, noise analysis has also been recently used to determine the charge carrier transport and the degradation phenomena in polymer:fullerene solar cells [25,26].…”