Colloquium

Monday 20 March 2023

Speaker

Andreas Kaltzoglou

Affiliation

Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Greece

Title

Advanced Materials Synthesis for Photovoltaic and Thermoelectric Applications

Location

Location

Room A2 (A115-A117) of CSD Building (ground floor, north wing)

Time

16:00

Language

English

Abstract

The lecture will present the advances in the fields of photovoltaic and thermoelectric materials, emphasizing on the preparation method and the morphology of the chemical compounds. It is well known that solar cells are one of the main renewable energy sources. In quest of materials more efficient than silicon, the research focuses on semiconductors such as GaAs, CuIn_1-xGa_xSe₂ (0 ≤ x ≤ 1) as well as halide perovskites (CH₃NH₃PbI₃). Despite the high power-conversion efficiencies of the 3rd generation solar cells, this technology has not yet reached commercialization, either due to the toxicity of the elements, e.g. As, or due to the instability of the compounds, e.g. hydrolysis of CH₃NH₃PbI₃. Therefore, novel chemical compounds are sought with lower toxicity and higher stability. In a similar manner to photovoltaic materials, thermoelectric materials usually exhibit semiconducting behavior, as in tellurides (Bi₂Te₃), clathrates (Cs₈Sn₄₄), skutterudites (Yb_0.2Co₄Sb₁₂), and tetrahedrites (Cu_10.5Ni_1.5Sb₄S₁₃). So far, their applications are limited to thermocouples for temperature measurement (Seebeck effect) and specialized cooling systems, such as portable refrigerators and computer processors (Peltier effect). The energy recovery from wasted heat in the form of electricity is the main goal for thermoelectric use, for example on engine exhausts and on building surfaces. Apart from the synthesis methods in liquid or solid state, the chemical composition – crystal structure – physical properties relations will be analyzed.