Perovskite-CIGS Monolithic Tandem Solar Cells with 29.7% Efficiency: A Numerical Study

Abstract

Tandem solar cells have higher efficiency than single-junction devices owing to their wide photon absorption range. A wide band gap (E g ) absorber absorbs the higher-energy photons in the top cell. In contrast, a comparatively low band gap absorber material is utilized in the bottom cell to absorb the filtered low-energy photons. Consequently, thermalization and transparent energy losses are overshadowed by the top subcell (Top sc ) and the bottom subcell (Bottom sc ), respectively. However, to achieve the best efficiency from a tandem design, the choice of active material in the Top sc and the Bottom sc plays an important role. Therefore, in this proposed study, a tandem solar cell comprising a perovskite (E g 1.68 eV)-based top cell and a copper indium gallium selenide (CIGS, E g 1.1 eV)-based Bottom sc has been designed and analyzed. A state-of-the-art Me-4PACz ([4-(3,6-dimethyl-9 H -carbazol-9-yl)butyl] phosphonic acid) hole transport layer (HTL) in the perovskite solar cell reported in the previous literature has been considered for the top cell, whereas a calibrated CIGS-based Bottom sc with 16.50% efficiency is designed. Both the Top sc and the Bottom sc are examined for the tandem configuration using filtered spectra and current-matching techniques. In perovskite/CIGS tandem design, an ideal tunnel recombination junction uses Me-4PACz and ITO layers. In a tandem configuration with matched current density at an absorber thickness of 347 nm for Top sc and 2.0 μm for Bottom sc, the device delivered an open-circuit voltage ( V OC ), current density ( J SC ), and fill factor (FF) of 1.92 V, 20.04 mA/cm 2, and 77%, respectively, resulting in an overall power conversion efficiency (PCE) of 29.7%. The results reported in this work would be beneficial for the development of perovskite-CIGS-based monolithic tandem solar cells in the future.

Topics & Concepts