Structural, Optical, Electrical, and Photoelectrochemical Properties of AgInSe ₂ Thin Films Prepared by Chemical Bath Deposition

The increasing demand for low‐cost and efficient optoelectronic materials has intensified research on I–III–VI ₂ chalcogenides, particularly silver indium diselenide (AgInSe ₂ ), due to its suitable direct band gap and strong optical absorption. However, issues such as defect‐induced recombination, low carrier mobility, and limited photoelectrochemical (PEC) efficiency restrict its practical applications. In this work, AgInSe ₂ thin films were synthesized using a simple and cost‐effective chemical bath deposition method. Structural analysis confirmed the formation of phase‐pure chalcopyrite structure with preferential orientation, while SEM revealed a uniform and compact morphology. Optical studies showed a direct band gap of 1.20 eV with a high absorption coefficient. Electrical measurements indicated semiconducting behavior with carrier concentration decreasing from 8.7 × 10 ¹⁷ to 1.1 × 10 ¹⁷  cm ⁻³ and mobility increasing from 9.9 × 10 ⁻³ to 13.5 cm ² /V·s as temperature increased. The positive Seebeck coefficient (437–549 µV/K) confirmed p‐type conductivity. PEC studies exhibited enhanced performance with photocurrent density up to 1.2 mA/cm ² , a photovoltaic of 0.62 V, and an efficiency of 1.35%. The results demonstrate improved transport and photoresponse properties due to controlled growth. Further enhancement is recommended through doping and interface engineering for photovoltaic applications.