Numerical analysis of a hysteresis model in perovskite solar cells

Abstract

Previously, we proposed that the polarization and capacitive charge in CH 3 NH 3 PbI 3 screens the external electric field that hinders charge transport. We argue here that this screening effect is in significant part responsible for the power conversion characteristics and hysteresis in CH 3 NH 3 PbI 3 photovoltaic cells. In this paper, we implement capacitive charge and polarization charge into the numerical model that we have developed for perovskite solar cells. Fields induced by these two charges screen the applied hindering field, promote charge transport, and improve solar cell's performance, especially in solar cells with short diffusion lengths. This is the reason why perovskite solar cells made from simple fabrication methods can achieve high performance. More importantly, with relaxations of capacitive charge and polarization charge, we quantitatively reproduce experimental "anomalous" hysteresis J-V curves. This reveals that both polarization relaxation and ions relaxation could contribute to anomalous hysteresis in perovskite solar cells.

Perovskite solar cells: short lifetime and hysteresis behaviour of current–voltage characteristics

“…Indeed, if the ions migrate from one side to the other, charge distribution, capacitance of the device and internal electric field within the device will change, causing the changes in I-V curves. Recent theoretical modelling also shows hysteresis in I-V curves due to ion-migration, very similar to experimentally measured results [13,14].…”

“…It has paramount importance in understanding this phenomenon taking place in PSCs in order to overcome this detrimental effect. Researchers have been working on this subject and many reports [11][12][13][14][15][16] are already in the public domain. These reports consider migration of ions such , iodide (I − ) and various other photo-induced ions within the device, polarisation during I-V measurements, and hence causing the changes in shape of the I-V curves.…”

“…This behaviour can also be other way around depending on the materials and device processing steps used [5]. Researchers have attempted to explain this behaviour in terms of ionic migration, polarisation effects and electronic charge trapping and de-trapping process within these devices [11][12][13][14][15][16].…”

Numerical modelling of ion-migration caused hysteresis in perovskite solar cells

“…It achieved 25% efficiency in 2019, a time span of just 10 years. In spite of their high efficiency owing to optimal bandgap high optical absorption coefficient, low bulk defects, they show current-voltage (I-V) hysteresis phenomenon (Zhou et al 2017;Anghel et al 2019;Richardson et al 1476;Daniel et al 2017;Reenen et al 2015;Miller et al 2016;Miyano et al 2018;Neukom et al 2017;Weber et al 2018;Shen et al 2672;Xiang et al 2019). The hysteresis is related to non-identical I-V characteristic in forward and reverse scan.…”

Hysteresis Analysis of Hole-Transport-Material-Free Monolithic Perovskite Solar Cells with Carbon Counter Electrode by Current Density–Voltage and Impedance Spectra Measurements

“…The hysteretic behavior has been studied intensively [ 17 , 18 , 22 ] and ion migration has been identified as one of the relevant origins of hysteresis in PSCs [ 17 , 23 , 24 ]. Morphological change, ionic migration within the cell, ferroelectric polarization by the rotating methylammonia (MA) cations, trapping/detrapping of charges, capacitive charge accumulation/space charges, chemical degradation, and light-doping have been proposed as candidate mechanisms for hysteresis in PSCs [ 20 , 21 , 25 , 26 , 27 , 28 , 29 , 30 ]. A computational model was developed to investigate the dominant physical phenomenon related to hysteresis in J–V characteristics of PSCs [ 30 ].…”