Impedance Spectroscopy of Perovskite Solar Cells: Studying the Dynamics of Charge Carriers Before and After Continuous Operation

Abstract

The issue of long‐term stability is one of the main obstacles challenging the progress of perovskite solar cells (PSCs). To alleviate this issue, a thorough understanding of the degradation mechanisms of the device is required. Herein, electrochemical impedance measurements in combination with maximum power point (MPP) tracking are applied to characterize PSCs, aiming to gain an understanding of the charge carrier dynamics in the photoactive bulk and at the contact‐absorber‐interfaces under operation. Electrochemical impedance spectroscopy (EIS) results show that the device charge transport resistance and interface capacitance associated with charge accumulation at the interfaces are both increasing upon continuous operation. This suggests ion migration from the photoactive perovskite layer to the charge transport layer interfaces leaving defects in the bulk. This suggests that reduction of the device performance upon continuous operation is mainly related to the changes in the bulk of the photoactive perovskite film and ions migration.

Electrodeposited PEDOT:PSS-Al2O3 Improves the Steady-State Efficiency of Inverted Perovskite Solar Cells

“…Furthermore, in the impedance spectrum (IS), the first arc at high frequencies is attributed to the charge transfer resistance and recombination resistance (R 1 ) [ 39 ]. The capacitance of this arc is of the geometrical type and is due to the perovskite material (C 1 ) [ 80 ]. The second arc at intermediate frequencies is due to the recombination resistance R 2 , although it is usual to add R 1 and R 2 to estimate this resistance [ 39 , 79 ].…”

“…The second arc at intermediate frequencies is due to the recombination resistance R 2 , although it is usual to add R 1 and R 2 to estimate this resistance [ 39 , 79 ]. The capacitance of the second arc C 2 represents the charge accumulation at the cell interfaces, which causes defects in the perovskite leading to recombination [ 44 , 80 ]. This capacitance increases rapidly near the maximum power point (MPP) of the solar cell.…”

Temperature‐ and Bias‐Dependent Degradation and Regeneration of Perovskite Solar Cells with Organic and Inorganic Hole Transport Layers

“…The relationship between the capacitance decay rate and the rate of ion migration should be further explored without the simplifying assumptions of the TID model. Steady-state capacitance changes have been previously reported which point to an accumulation of charge at a contact layer, [49] and we should determine if indeed migration into or out of the HTL under bias can also trigger both the capacitance changes and the FF changes evident in Figure 1a. To this end, simulations were conducted using SCAPS-1D software.…”

High-performance wide bandgap perovskite solar cells fabricated in ambient high-humidity conditions

“…In addition to the set of morphological, structural and optoelectronic characterization techniques employed in this work, further insight into the role of the resulting bulk and interfaces' properties on the PSCs' transport mechanisms can be gained via electrochemical impendance/admittance analysis, which can also probe and provide a better understanding of the charge distribution and transfer within the PSC structure, including ion migration and, thus, hysteresis effects, as discussed in related works [38,[65][66][67][68].…”