Efficiency enhancement of CZTSSe solar cells via screening the absorber layer by examining of different possible defects

Abstract

This study represents the investigation of earth-abundant and non-toxic CZTSSe absorber materials in kesterite solar cell by using the Finite Element Method (FEM) with (1) electrical, and (2) optical approaches. The simulated results have been validated with the experimental results to define guidelines for boosting the cell performance. For improving the cell efficiency, potential barrier variations in the front contact, and the effect of different lattice defects in the CZTSSe absorber layer have been examined. Controlling the defects and the secondary phases of absorber layer have significant influence on the cell performance improvement. Previous studies have demonstrated that, synthesis of CZTSSe:Na nanocrystals and controlling the S/(S + Se), Cu/(Zn + Sn), and Zn/Sn ratios (stoichiometry) have significant effects on the reduction of trap-assisted recombination (Shockley–Read–Hall recombination model). In this work, a screening-based approach has been employed to study the cell efficiency over a wide range of defect densities. Two categorized defect types including benign defects ($${N}_{t}<{10}^{16}$$ N t < 10 16 cm−3 , Nt defines trap density) and harmful defects $${(N}_{t}>{10}^{16}$$ ( N t > 10 16 cm−3) in the absorber bandgap in the CZTSSe solar cell, by analyzing their position changes with respect to the electron Fermi level (Efn) and the Valence Band Maximum positions have been identified. It is realized that, the harmful defects are the dominant reason for the low efficiency of the kesterite solar cells, therefore, reducing the number of harmful defects and also total defect densities lead to the power conversion efficiency record of 19.06%. This increment makes the CZTSSe solar cells as a promising candidate for industrial and commercial applications.

Spectroscopy and Theoretical Modeling of Phonon Vibration Modes and Band Gap Energy of Cu2ZnSn(SxSe1–x)4Bulk Crystals and Thin Films

“…It is also worth remembering that the formation of pairs of antisite defects Cu Zn and Zn Cu is one of the most common methods in these compounds (it reduces E g , when forming donor–acceptor pairs Zn Cu + + Cu Zn – ). − These defect complexes can act as recombination centers for the charge carriers, thereby limiting the open-circuit voltage ( V oc ) and, hence, the efficiency of CZTSSe-based photovoltaic devices . This is why, along with the ever-rising number of experimental publications in this area, the number of theoretical studies is also growing. ,− …”

Numerical Modeling and Performance Evaluation of SnS Based Heterojunction Solar Cell with p+ SnS BSF Layer

“…Hence the value of the defect density needs to be taken care of in a very signi cant manner [ 31 ]. In this work, the value of defect density was varied from 10 10 cm -3 to 10 18 cm -3 to study the impact on the photovoltaic performance of the SnS based solar cell.…”

Comprehensive study of anomalous hysteresis behavior in perovskite-based solar cells

“…The device properties of perovskite-based solar cells have been simulated utilizing the Finite Element Method (FEM) Method 14 . We calculate cell parameters and performance using the numerical solution of the basic semiconductor equations; these equations constitute the Poisson equation (Eq.…”

“…We de ne new equations (Eqs. (12)(13)(14)) that consider the ion ux through the ETL and HTL layers. A schematic of anions, and cations diffusion to the ETL, and HTL are shown in Figs.…”