Theory for IMPS on Rough and Finite Fractal Dye Sensitized Solar Cell

Abstract

A generalized theoretical model of intensity modulated photocurrent spectroscopy (IMPS) for the random morphology in a dye sensitized solar cell (DSSC) under uniform illumination is developed. The generalized IMPS expression for the disordered semiconducting/conducting glass interface of a DSSC is obtained in term of power spectral density of roughness. Influence of surface roughness on the dynamic response of DSSC originate due to the coupling of characteristic phenomenological and morphological length scales. A detailed analysis of IMPS response is performed over finite self- affine fractals to highlight roughness induced anomalies and cause of photocurrent enhancement. The IMPS of a rough DSSC exhibit three characteristic frequency regimes: lifetime of charge carrier dependent low frequency regime, surface irregularity dependent intermediate power-law regime and diffusion controlled high frequency regime. Finally, our theory facilitates the understanding of dynamics and kinetics of charge carriers under the influence of ubiquitous surface disorder.

Sb2S3 Thickness-Related Photocurrent and Optoelectronic Processes in TiO2/Sb2S3/P3HT Planar Hybrid Solar Cells

“…Furthermore, IMPS and IMVS, as the powerful dynamic photoelectrochemical methods in dye-sensitized solar cells [31] and perovskite solar cells [32], have been applied to study the charge transport dynamics in this work. IMPS/IMVS measures the photocurrent/photovoltage response to a small sinusoidal light perturbation superimposed on the background light intensity under short-circuit/open-circuit condition [31–33]. The measured IMPS or IMVS responses appear in the fourth quadrant of the complex plane with a shape of the distorted semicircle (Fig.…”

“…The time constant τ defined by the frequency ( f min) of the lowest imaginary component of IMPS or IMVS response is an evaluation of the transit time τ IMPS for the electrons to reach the collection electrode under short-circuit condition or the electron lifetime τ IMVS related to interfacial charge recombination under open-circuit condition. According to the relation τ = (2π f ) −1 [31–35], τ IMPS and τ IMVS in the devices were calculated (Table 1). The increased τ IMPS suggests a longer transport path of charges to collection electrode, whereas the unchanged τ IMVS infers the same interfacial charge recombination [33].…”

“…The increased τ IMPS suggests a longer transport path of charges to collection electrode, whereas the unchanged τ IMVS infers the same interfacial charge recombination [33]. The interfacial charge collection efficiency η c is typical considered as η c = 1- τ IMPS / τ IMVS [31–35]. Obviously, the longer transport time of the τ IMPS and the short interfacial charge recombination lifetime of the τ IMVS would cause a worse charge collection and vice versa.…”

Correcting unintended changes in electroluminescence perturbation for reliable light intensity modulated spectroscopies

“…Commonly, IMPS and IMVS spectra are shown in Nyquist representation, where the respective transfer functions are plotted representing the negative imaginary parts -Q′' and -W′', as a function of the real parts, Q′ and W′ (see figure 1). In this representation, most typical spectra include one or several arcs in the first quadrant [3,4,19] and, in some cases, loops and/or tails in the second [4,20] and/or the fourth quadrant [21,22].…”

Dynamic Photocurrent Response of CuO-Nanoarray-Based Photoelectrodes: Heterostructure and Small Electric Field Effects

“…The IMPS method is a dynamic photoelectrochemical method that has been successfully used as an effective tool for investigating the dynamics of charge generation and transport in photoelectrodes and photovoltaic devices and has provided mechanistic insight into basic photoelectric processes. 8,9 When IMPS measurements are performed, a bias voltage is applied in photovoltaic devices to study effects of the electric field on the dynamics of charge transport, which has been reported in solar cells. 8 However, to the best of our knowledge, no study on the use of IMPS method has been conducted to examine the effect of an external electric field on CuO-based photoelectrodes in photoelectrochemical cells.…”