Dynamic electrical behavior of halide perovskite based solar cells

Abstract

A dynamic electrical model is introduced to investigate the hysteretic effects in the I-V characteristics of perovskite based solar cells. By making a simple ansatz for the polarization relaxation, our model is able to reproduce qualitatively and quantitatively detailed features of measured I-V characteristics. Pre-poling effects are discussed, pointing out the differences between initially over- and under-polarized samples. In particular, the presence of the current over-shoot observed in the reverse characteristics is correlated with the solar cell pre-conditioning. Furthermore, the dynamic hysteresis is analyzed with respect to changing the bias scan rate, the obtained results being consistent with experimentally reported data: the hysteresis amplitude is maximum at intermediate scan rates, while at very slow and very fast ones it becomes negligible. The effects induced by different relaxation time scales are assessed. The proposed dynamic electrical model offers a comprehensive view of the solar cell operation, being a practical tool for future calibration of tentative microscopic descriptions.Comment: 8 pages, 6 figures, Supplemental material, to appear in Solar Energy Materials & Solar Cell

Normal and Inverted Hysteresis in Perovskite Solar Cells

“…However, depending on the pre-poling conditions I (nl) c can reach magnitudes similar to the measured current [30].…”

“…Then, an equivalent circuit model with constant capacitance was proposed [29]. The DEM, recently formulated by our group [30], is also based on an equivalent circuit, but includes a capacitor accounting for non-linear polarization effects as depicted in Fig. 1.…”

The Influence of the Relaxation Time on the Dynamic Hysteresis in Perovskite Solar Cells

“…Since P 0 > 0 for each relaxation time, normal hysteresis behavior is obtained for any τ as explained in Ref. [4]: the hysteresis is diminished for very small and very large scan rates, while the short-circuit current I sc increases with α. However, modifying τ the overall picture regarding the dynamic hysteretic effects is changing.…”

“…We base our analysis on the dynamic electrical model (DEM) [4], which is able to accurately reproduce the experimental J-V characteristics. In particular, a unified picture comprising normal (NH) and inverted (IH) hysteresis in the same device structure subject to different bias pre-conditioning was recently given by DEM, validated by J-V measurements [5].…”

“…e-mail: nemnes@solid.fizica.unibuc.ro DEM provides a time dependent description of the J-V characteristics, by solving the coupled system of differential equations with given initial conditions as described in detail in Refs. [4,5]:…”