Grazing Incidence Wide Angle X-ray Scattering (GIWAXS): GIWAXS measurements were performed at 8-IDE beamline of the Advanced Photon Source at Argonne National Laboratory using an incident beam energy of 10.86 keV on a two-dimensional detector (PILATUS) with an incident angle of 0.14°. For sample preparation, ZnO was firstly deposited on a Si wafer followed by the photoactive layer deposition and thermal annealing the same way that all OSC devices were fabricated. From GIWAXS measurement, 2D scattering images were obtained and converted to 1D scattering profiles by using the beamline GIXSGUI package written for MATLAB. For molecular orientation analysis, the 1D GIWAXS pattern of intensity versus scattering vector was azimuthally integrated from -10° < χ < -80° with 5° interval to yield an intensity versus the χ angle. Film thickness measurements: Film thickness was measured by using the Bruker Dektak XT profilometry with the stylus force of 3 mg with a scan range of 1000-2000 µm. For thickness measurements, a part of the film was removed with a cotton swab with toluene solvent. The thickness measurements were repeated on 3-5 different positions to obtain the average and standard deviation.