Semiconductor-Transparent Conductive Oxide (SC-TCO) Inorganic Nanocomposite Thin Films for Photovoltaic Energy Conversion
Authors : Grace Shih, Cary Allen, B.G. Potter
Semiconductor nanocrystals (quantum dots (QDs)) are widely researched as optical sensitizers in third-generation photovoltaic (PV) devices. Improvements in PV energy conversion efficiency are anticipated through the manipulation of nanocrystal size and spatial distribution within the heterojunction thus influencing the optical absorption and carrier transport properties of the device. The present work investigates the impact of germanium (Ge) within an indium-tin-oxide (ITO) conductive matrix. Ge-ITO thin films are produced via a multisource, sequential, RF-magnetron sputter deposition technique. The approach enables the variation of semiconductor volume fraction and phase distribution by adjustment of the relative substrate exposure times to each sputtering source during deposition. Spectrally resolved photoconductivity measurements of the resulting nanocomposite films confirm the development of a photocurrent under frequency-selective optical excitation of the Ge nanocrystal ensemble. Photovoltaic performance is examined by incorporating the nanocomposite into a heterojunction structure.