Influence of silver incorporation on the structural, optical and electrical properties of spray pyrolyzed indium sulfide thin films

• In situ silver doping of the indium sulfide window layers.
• A new and cost effective route to dope spray pyrolyzed thin films.
• Enhanced photosensitivity of the films even at very low doping concentrations.
• Structural phase control with in situ silver doping.
• Tailoring optical and electrical properties via in situ silver doping.

In this study, a simple and cost effective route to tailor the structural, electrical and optical properties of the indium sulfide (In2S3) thin films have been presented. Effects of silver incorporation via in situ doping have been investigated in detail using various characterization tools. XRD patterns confirmed that all of the spray-pyrolyzed films had nanocrystalline nature. Both XRD and Raman analysis confirmed a phase change occurred at the silver concentrations exceeded 10% of the indium concentration in the precursor solution. Raman spectra of the films also revealed that bonding of sulfur with silver atoms became apparent when the silver concentration was exceeded 10%. UV–VIS spectrum showed that increase in silver atomic percent in the films caused decreasing the optical band gap. Moreover, it was observed that silver incorporation enhanced the light sensitization of the In2S3 thin films. The photosensitivity of the films with 20% silver was about 2 × 103, which was 10× higher than that of samples with no silver. This indicates the huge potential for using silver incorporated In2S3 thin films as the window layer of thin film solar cells. Furthermore, all of the sprayed films were n-type and showed a room temperature resistivity varying between ∼102 and ∼105 Ω cm. As a result, morphological, structural, optical and electrical characterization of the spray pyrolyzed In2S3 films provided that in situ root of silver incorporation used in this study is a very promising method to tailor the physical properties of the In2S3 for thin film solar cell applications even at very low silver concentrations.