Upconverter loaded MoS2 counter electrode for broadband dye-sensitized solar cell applications

An interesting approach of including an upconverter in the MoS 2 counter electrode can yield broadband light harvesting Pt-free DSSC assembly. Here different upconverter (UC) nanoparticles (Yb, Er incorporated NaYF 4 , YF 3 , CeO 2 & Y 2 O 3 ) were synthesized and loaded in MoS 2 thin film by hydrothermal method. The inclusion of UCs in MoS 2 films exposed without any secondary formation of upconverters and the uniform deposition of the films are confirmed through XRD and FESEM analysis respectively. The absorption spectrum (UV-Vis-NIR) confirms the increase in absorption intensity in visible and NIR regions due to the incorporation of UCs. Under 980 nm excitation, the UCs-loaded MoS 2 films show emission in blue (450–490 nm), green (520–540 nm) and red (600–700 nm) regions due to the f-f inner transition occurring in the Er ions. The oxide and fluoride UCs-based DSSCs were fabricated with an FTO/TiO 2 /N719/Triiodide electrolyte/UC@MoS 2 /FTO assembly. Oxide UCs show greater electrocatalytic activity, which might be owed to the films exposed with more catalytic active sites favourable for ion transportation in the I − /I − 3 electrolyte. Among them, higher photoconversion efficiency (PCE) of 7.1% was witnessed for (Y 2 O 3 : Er, Yb) @MoS 2 counter electrode-based DSSC which is due to the good conductivity (R S ) of the film, the longer electron lifetime and photon harvesting enhancement by upconversion process. It is notably convinced that the UC-loaded MoS 2 films can be used as an effective counter electrode for the possible realization of upconverter DSSC and used for broadband light absorption.