2018 Materials science lecture series: advanced materials - 7 December 2018
Dec 07, 2018 - 10.30 uur
Agoralaan Gebouw D
Lokaal Room C105
Mevrouw Aslihan BABAYIGIT
MRS/E-MRS joint chapter of Hasselt University: 2018 materials science lecture series: advanced materials.
Speaker: Dr. Tayebeh Ameri, University of Munich-Germany
Ternary Sensitization of Organic Solar Cells, a Multifunctional
Concept to Boost Power Conversion
Chaired by: Prof. Dr. Koen Vandewal and Prof. dr. Wouter Maes, IMO-IMOMEC, Hasselt University
Friday 7 December 2018, 10:30 -11:30
Room C105, Building D, Hasselt University, Campus Diepenbeek.
The unique selling points of organic photovoltaics (OPVs), such as excellent light harvesting capability, freedom of form, color and transparency, environmental friendliness, easy scalability and lower manufacturing costs based on roll-to-roll printing methods, position this technology for the mobile power market, and this most properly reflects the state of the art in commercialization. An important milestone towards OPV commercialization has been surpassed by reaching a power conversion efficiency (PCE) of over 13%. However, despite the significant improvements achieved, the PCE of OPVs has to be increased to compete with commercial inorganic solar cells. The main limitation is due to the intrinsic narrow absorption window (~100-200 nm) of polymers compared to inorganic semiconductors such as Si, which makes it challenging to fully cover the solar spectrum with a single junction device. Furthermore, due to the low mobility of the photoactive materials, organic solar cells present a limited thickness, typically around 100 nm, that dramatically limits light harvesting.
To overcome the absorption limitation, ternary blend organic solar cells represent one of the dominant strategies that has been explored in the last decade. The outstanding advantage of ternary blends consists of maintaining the simplicity of the processing conditions used for single active layer devices. Moreover, all the optimization strategies developed for binary cells can be also effectively applied for ternary solar cells. In this elegant configuration all three photovoltaic parameters (VOC, JSC, FF) can be tackled simultaneously or individually by optimizing the ratio between the three materials used in the photoactive layer. In this presentation, we will discuss the achieved results for various prototype organic and hybrid organic-inorganic ternary systems with a central focus on the fundamental complexity of microstructure and charge transport mechanisms. Importantly, we will explain the key issues that result in modified recombination mechanisms and consequently improved FF and VOC in high efficiency ternary solar cells.