Probing the Low-Frequency Response of Impedance Spectroscopy of Halide Perovskite Single Crystals Using Machine Learning

Abstract

Electrochemical impedance spectroscopy (EIS) has emerged as a versatile technique for characterization and analysis of metal halide perovskite solar cells (PSCs). The crucial information about ion migration and carrier accumulation in PSCs can be extracted from the low-frequency regime of the EIS spectrum. However, lengthy measurement time at low frequencies along with material degradation due to prolonged exposure to light and bias motivates the use of machine learning (ML) in predicting the low-frequency response. Here, we have developed an ML model to predict the low-frequency response of the halide perovskite single crystals. We first synthesized high-quality MAPbBr3 single crystals and subsequently recorded the EIS spectra at different applied bias and illumination intensities to prepare the dataset comprising 8741 datapoints. The developed supervised ML model can predict the real and imaginary parts of the low-frequency EIS response with an R 2 score of 0.981 and a root mean squared error (RMSE) of 0.0196 for the testing set. From the ground truth experimental data, it can be observed that negative capacitance prevails at a higher applied bias. Our developed model can closely predict the real and imaginary parts at a low frequency (50 Hz–300 mHz). Thus, our method makes recording of EIS more accessible and opens a new way in using the ML techniques for EIS.

In-Line Electrochemical Impedance Spectroscopy for Real-Time Circuit Identification and Interpretation in Metal Halide Perovskite Single Crystals

“…The EIS Nyquist spectra, acquired under bias voltages ranging from 0.1 to 1.5 V, reflect the evolving electrical behavior of the MAPbI 3 SC, as indicated by the correspondingly decreasing radii of the semicircular Nyquist graphs in Figure . This trend of decreasing Z ′ and Z ″ continues in each corresponding increasing bias voltage . As we increased the bias voltage across the MAPbI 3 SC, the EC type of the EIS spectra transformed.…”

Understanding the Origin and Evolution of Resistive Effects during Switching Action in MAPbBr3 Single Crystals

“…In addition to this, the effect and underlying mechanism of hysteresis in relation to device performance can be understood with the help of impedance spectroscopy (IS). , The presence of hysteresis or accumulation of ions will lead to a significantly higher value of capacitance at low frequency. Tisdale et al studied the effect of different contact materials on MAPbBr 3 crystals and found that the gold (Au) contact leads to high resistive and capacitive effects at lower frequencies in electrochemical impedance spectroscopy (EIS) spectra.…”

Lead-Free Organic Manganese (II) Bromide Hybrid with Highly Efficient and Stable Green Emission for UV Photodetection

“…As an important semiconductor functional material, lead halide perovskite plays an important role in the light, display, and photodetector fields due to its excellent optoelectronic properties [1][2][3][4][5][6]. Although lead halide perovskites have achieved a series of remarkable results [7,8], their inherent toxicity and poor stability limit their further applications in optoelectronic devices. Therefore, the key to solving these problems is to explore new non-toxic and stable materials.…”