Shift your interest away from the device level to characterize at the material level: active or component layers. Reap the rewards of a spectrophotometer methodology to establish, and spectrally resolve, the extent to which the sample reflects (and transmits, in the case of thin films) the incident light. The characterization of textured surfaces and diffusing thin films and coatings, including anti-reflective coatings and transparent electrodes, is enabled by a calculation of total reflectance/total transmittance. Total transmittance spectra of 100 nm Mg-doped CuCrO2 thin films deposited on quartz substrate and annealed at various temperatures. Measurement data courtesy of CIRIMAT, Toulouse. J. Mater. Chem. C, 2015, 3, 6012. Collecting the totality of light reflected into the hemisphere above the sample is the prerequisite for the measurement of total reflectance; the collection of the totality of light transmitted into the hemisphere behind the sample is the prerequisite for the measurement of total transmittance. Hemispheric light collection is enabled by an integrating sphere, whilst a wavelength tunable monochromatic light permits sample illumination. Systems in which a si...