UC Santa Barbara

Organic semiconductors tend to have highly ordered, anisotropic morphologies. These structural anisotropies lead to optical anisotropies which we have shown directly affect the efficiency of photonic devices such as organic photovoltaics (OPVs). Measuring the direction-dependent optical properties of organic films would thus give unique insights into film structure and inform the design of organic optoelectronics. In this work we develop momentum-resolved spectroscopies to precisely measure the emitting and absorbing dipole strengths as well as complex refractive indices of uniaxial organic films. We then demonstrate how these techniques can be used to investigate film morphology by measuring the tilt angle and processing-dependent structural changes in the polymer system P(NDI2OD-T2). Finally, we show how molecular orientation impacts device properties by studying changes in surface plasmon dispersion and photoluminescence enhancement in films of the small molecule p-SIDT(FBTTh2)2 on gold.