A simulation model for PLZT based ferroelectric photovoltaic devices, II. Influence on charge transport and photovoltaic parameters with ITO top and Pt bottom electrodes

Abstract

This work is an extension of our previously developed photovoltaic (PV) model with ferroelectric PLZT as photoactive layer, metal Pt as top and bottom electrodes. Pt electrodes result in good ferroelectric properties but lower PV output, as seen from our model. We developed a new PLZT PV model with ITO as top electrode and Pt as bottom electrode using a semiconducting thin-film optics simulation (SETFOS) software. Dependence of PV characteristics such as open circuit voltage ($V_{OC})$ and short circuit current density $(J_{SC}$) and charge transport properties such as carriers’ concentration, current density and recombination on the model parameters were investigated. The parameters including thickness of interface layer (between PLZT and ITO top electrode), thickness and work function of ITO top electrode were optimized, which were used to obtain $V_{OC}$ and $J_{SC}$ of the simulated model. $V_{OC}$ and $J_{SC}\mathrm{ }$of the simulated and the experimental device matched closely. Charge carriers’ concentration and current density of the PLZT layer with ITO and Pt as top electrodes were compared. These properties show that ITO top electrode enhances the charge transport in PLZT, which results in higher $V_{OC}$ and $J_{SC}$ of the PV device.

Abbreviations. PV: Photovoltaic; FE: ferroelectric; PLZT: lanthanum doped lead zirconate titanate; SETFOS: semiconducting thin-film optics simulation software; ITO: Indium tin oxide; Pt: Platinum; E_c: conduction band; E_v: valence band, $J_{SC}$: short circuit current density, $V_{OC}$: open circuit voltage; PCE: power conversion efficiency, $J_{rec}$: recombination current; IL: interface layer; ITO_et: ITO top electrode; Pt_et: Pt top electrode, $J_{\text{total}}$: total current, $J_n$: electron current density, $J_p$: hole current density, $n:$ electron concentration, $p:$ hole concentration

KEYWORDS:

• PLZT
• ferroelectric
• photovoltaic
• ITO
• transparent electrode
• charge transport

Acknowledgements

One of the author (VB) acknowledges the Electrical and Computer Engineering (ECE) Department at The University of Alabama, Tuscaloosa, USA for Graduate Teaching Assistantship. Authors extend their thanks to Dr. Dawen Li of ECE department for providing access to the SETFOS software and to Lieven Penninck of Fluxim, Switzerland for fruitful discussions on software.