Effects of Solvent Additive and Micro-Patterned Substrate on the Properties of Thin Films Based on P3HT:PC70BM Blends Deposited by MAPLE

Lately, there is a growing interest in organic photovoltaic (OPV) cells due to the organic materials' properties and compatibility with various types of substrates. However, their efficiencies are low relative to the silicon ones; therefore, other ways (i.e., electrode micron/nanostructuring, synthesis of new organic materials, use of additives) to improve their performances are still being sought. In this context, we studied the behavior of the common organic bulk heterojunction (P3HT:PC70BM) deposited by matrix-assisted pulsed laser evaporation (MAPLE) with/without 0.3% of 1,8-diiodooctane (DIO) additive on flat and micro-patterned ITO substrates. The obtained results showed that in the MAPLE process, a small quantity of additive can modify the morphology of the organic films and decrease their roughness. Besides the use of the additive, the micro-patterning of the electrode leads to a greater increase in the absorption of the studied photovoltaic structures. The inferred values of the filling factors for the measured cells in ambient conditions range from 19% for the photovoltaic structures with no additive and without substrate patterning to 27% for the counterpart structures with patterning and a small quantity of additive.

Automated summary

There is a growing interest in organic photovoltaic (OPV) cells due to their properties and compatibility with various substrates. However, their efficiencies are low compared to silicon cells, and improvements are being sought through electrode nanostructuring, synthesis of new materials, and use of additives. In this study, the behavior of a common organic bulk heterojunction was examined when deposited on different substrates and with/without an additive. The results showed that the morphology of the films can be modified and their roughness decreased with the addition of a small quantity of additive. Micro-patterning of the electrode also increased the absorption of the photovoltaic structures.