In Situ Structural Analysis of Blade Coated Dilute Donor Organic Solar Cells

Whilst organic solar cells (OSCs) have now reached efficiencies necessary for commercialization, their current high cost is prohibitive for most applications. The exception to this is semi-transparent OSCs, where the tuneable absorption of the active layer can be uniquely exploited to create power-generating, semi-transparent energy sources. These hold great potential for building-integrated photovoltaics and net zero architecture. A common way to achieve this transparency is via a reduced donor content in the OSC active layer, in so called 'dilute donor cells'.
In this work we explore printing such dilute donor systems, using donor PTQ10 and acceptor Y12, via blade coating; alongside structural analysis to understand the relationship between printing conditions and photovoltaic performance.
We show results from a custom, blade coater setup used to measure in-situ grazing incidence wide angle x-ray scattering (GIWAXS) at the Diamond Light Source synchrotron, under a range of conditions. We see differences in crystallization and drying dynamics depending on stage temperature and donor content, and relate these to device performance for blade coated OSCs. Grazing incidence small angle x-ray scattering (GISAXS) and a range of device based optoelectronic measurements are also shown to provide an overview of structure-function relationships. We believe this work provides an important insight into how blade-coating conditions impact film morphology, and therefore how printing conditions can be designed for optimum semi-transparent OSCs.