Explaining the molecular structure of the bulk heterojunction with simple electronic measurements and marcus-hush theory for squaraine: PCBM organic photovoltaic devices

A unique donor material for small molecule organic solar cells is shown to be opto-electrically tunable with thermal annealing. The system is characterized and shown to make working devices (PCE=1.1 +/- 0.3%). Examination of the spectral response of the devices before and after thermal annealing show an interesting decrease in spectral response that is explained by examining both the material properties and through application of Marcus-Hush theory. The proposed explanation could lay the groundwork for a predictive model to analyze potential device candidates.