Identification of recombination losses and charge collection efficiency in a perovskite solar cell by comparing impedance response to a drift-diffusion model

Abstract

Interpreting the impedance response of perovskite solar cells is significantly more challenging than for most other photovoltaics. Here we provide a way to obtain useful information from the spectrum using insights from drift-diffusion simulation.

In the Quest of Low‐Frequency Impedance Spectra of Efficient Perovskite Solar Cells

“…[12] However, Riquelme et al have shown that the R HF (not R LF ) can be considered as a true recombination resistance as both the resistances have different biases and illumination dependences. [19] Moreover, a similar slope, but with the opposite trend, is observed between R LF and C LF here, which indicates the same physical origin among them, but not with R HF . Based on our results and studies from the other authors following points are drawn: 1) R HF and R LF follow a similar dependence on the applied bias and illumination with a comparable slope.…”

“…[42] However, the decrease in recombination is clearly visible in the EIS spectra shown in Figure 3f Riquelme et al have simulated the low-frequency spectra peak in Im|Z| versus frequency plots, and showed that this peak shifts toward the high frequency as it is related to the high diffusion coefficient of ions. [19] The authors also stated that the associated low-frequency resistance, i.e., R LF should be the function of ions diffusion. Comparing the plots shown in Figure 2 and 3, it is established that shift in low-frequency peak in Im|Z| versus frequency plots and value of R LF and C LF has a no direct relation.…”

“…[16][17][18] In contrast, the low-frequency components, resistance (R LF ) and capacitance (C LF ), arise from the charging and discharging of the Debye layers because of the ion vacancy motion. [19] Thus, the C LF is mainly interpreted as the accumulation or apparent capacitance. [14,20] However, the interpretation of R LF is ambiguous.…”

“…Some reports suggest that R LF is related to ionic transport resistance, [21] whereas in another report, R LF was associated with recombination process as the behavior is the same as for the high-frequency resistance (R HF ). [19] Hence, because of this ambiguity, the question arises whether the R LF is associated with the recombination process and/or ionic transport.…”

Interfacial Defects Change the Correlation between Photoluminescence, Ideality Factor, and Open‐Circuit Voltage in Perovskite Solar Cells

“…The n id values measured from light intensity‐dependent V oc characteristics are popularly employed to understand which type of charge recombination prevails between the non‐radiative recombination via mid gap states created by defects, and radiative recombination via direct band‐to‐band transitions. [ 36–38 ] A value of n id approaching two was considered to result from a high defect density for non‐radiative SRH recombination, which in many cases could explain a low V oc . However, this analysis requires the premise that interfacial SRH recombination makes little contribution to V oc and n id .…”