Inorganic Cs₂TeX₆ (X = Cl, Br, I) Lead-Free Vacancy-Ordered Double-Perovskite Absorber-Based Single-Junction Solar Cells with a Higher Efficiency of ∼24%: Theoretical Insights

Abstract

We investigated the structural stability, density of states (DOS), optical and electronic properties of Cs2TeX6 (X = Cl, Br, I) vacancy-ordered double perovskites (VoDPs) using first-principles calculations. These VoDPs exhibit good structural stability based on tolerance factors, the Brown equation, and the formation energy. The calculated indirect bandgaps of Cs2TeX6 systems are also in agreement with the reported experimental values. We observed that the eigenband corresponding to the minima of the conduction band (CB) seems to be detached from the CB upon the consideration of spin–orbit coupling (SOC), and more band bending occurs at the “L” point. Overall, the high absorption coefficient (≈105 cm–1) of the Cs2TeI6 system, together with other optoelectronic properties in the visible spectrum range with moderate reflectance (∼33%), makes it a suitable photovoltaic (PV) absorber material. Furthermore, the PV performance of Cs2TeI6 material-based single-junction solar cell (SC) is investigated in the planar regular device configuration (n–i–p structure) for two different electron transport materials (ETMs: TiO2 and WS2). The optimum power conversion efficiency (PCE) of the FTO/n-WS2/Cs2TeI6/p-NiO SC configuration is found to be ∼23.74% together with open-circuit voltage (V oc), current density (J sc), and fill factor (FF) values of ∼1.094 V, 26.955 mA/cm2, and 80.53%, respectively. In addition, the photovoltaic response of the Cs2TeX6 absorber-based SC is also substantiated using the spectroscopic limited maximum efficiency (SLME) approach. Thus, the present work will play an important role in the realization of efficient lead-free VoDP-based single-junction SCs and other optoelectronic applications.

Electrospun Nanofiber-Based Electrolytes for Next-Generation Quasi-Solid Dye-Sensitized Solar Cells: A Review

“…The device was cost-effective, reusable, and had an exceptionally higher power conversion efficiency of 7.9%. After that, huge advancements have been achieved in this field, and to the best of our knowledge, a maximum photoconversion efficiency of around 30% was achieved. − Moreover, for commercial application the device should cross the threshold limit of operation of 20 years under outdoor conduction with a minimum of 10% cell efficiency . However, this liquid electrolyte-based DSSC still possesses several problems, including solvent evaporation, volatilization, easy leakage and flammability, which limit its long time practical outdoor application. , To find an alternative to liquid electrolytes, there is rising interest in using polymer-based solid-state electrolytes. ,− Currently, a flexible gel polymer electrolyte-based solid-state DSSC (ssDSSC) has been reported with an efficiency of 7% using 2,2′,7,7′-tetra­kis[N,N-di(4-meth­oxy­phen­yl)­amino]-9,9′-spiro­bi­fluor­ene (spiro-MeOTAD), an efficient hole-transport material (HTM), and that efficiency was lately improved to 12.3% by Hardin et al However, overall cell efficiencies of ssDSSCs are not good enough for practical application.…”