H. S. Hilal
An-Najah National University, Palestine
Title: Metal chalcogenide nano-film electrodes with 18% solar PEC conversion
Biography
Biography: H. S. Hilal
Abstract
Semiconductor (SC) surfaces are heavily investigated for photo-electrochemical (PEC) processes. While most of oncoming solar light lies in the visible or infrared regions, with only 5% in the UV region, SC materials with medium to narrow band gaps (2.5 -1.6 eV; 500 – 800 nm) are useful in visible light conversions. Unfortunately medium/narrow band gap semiconductors are unstable under photo-electrochemical (PEC) conditions. Therefore, stabilizing the monolithic SC surfaces is necessary. In earlier study we showed that metalloporphyrinato (MnTPyP) complexes chemically anchored to monolithic n-GaAs or n-Si surfaces enhanced their efficiencies but not efficiency. Later on, we showed that attaching these MnTPyP complexes with polymer (MnTPyP/Polym) coating to the SC surfaces improved both efficiency and stability. Due to their relatively high thickness (~0.5 mm) mono-crystalline SC materials are costly and demand special processes in manufacturing, as they need relatively high starting materials amounts. Therefore, nano-film SC electrodes are being heavily studied as alternative in PEC technology.The effect of MnTPyP/Polym matrices has been modeled here. Charge transfer mediation and SC flat-band lowering are proposed as shown in the Scheme. By lowering the SC flat band edges of the SC, and by facilitating the hole transfer across the SC/redox couple interface, the metalloporphyrin complex smartly enhanced short-circuit current, conversion efficiency and stability. The conversion values have not been preceded by metalchalcogenide nano-film electrodes before as far as we know. Detailed results and discussions will be presented.