3C SiC: Synthesis, Surface Properties and Application in Hybrid Solar Cells
Olivia Kettner
13:20 - 14:00 Friday 19 January 2018 PH01150

Silicon carbide (SiC) is an attractive material for applications in different fields spanning from high power electronics to material engineering, due to its versatile properties as high-temperature stable wide-band gap semiconductor, enormous chemical stability and high hardness.
This study is focused on the cubic polytype 3C-SiC. With the smallest bandgap (2.3 eV) among all polytypes, it is the most suitable one for photovoltaic (PV) applications. Still, SiC has been rarely considered for PV, where large surface area and low-cost production play an important role.
In the present case, the material is synthesized by a low-temperature bottom-up approach based on a sol-gel process combined with carbothermal reduction. This allows more cost-efficient fabrication of high-purity and high-surface area material than commonly used top-down methods via wet chemical etching or laser ablation of commercial SiC wafers. Further it is highly flexible, enabling synthesis of nano-/microparticles, pores and structures, and in-situ doping with donor or acceptor atoms.
As the heart of PV or related applications (e.g. photocatalysis) are interfacial charge-transfer processes - in this case between SiC homojunctions or at heterojunctions with another semiconductor, a catalyst, an electrode or an electrolyte - the composition and surface termination are of uttermost importance. They determine its performance in a potential application. A thorough investigation of the present sol-gel derived SiC material by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared (IR) analysis, reveals that polytype composition and surface termination are strongly dopant dependent.
Building onto this knowledge, the according SiC material has been implemented in organic/inorganic bulk-heterojunction hybrid PV devices, where it acts as the inorganic acceptor within an organic donor matrix with the common conjugated polymer poly (3-hexylthiophene). Thereby the photophysical and device physical behavior of the devices are investigated in reference to the applied dopant.