The invention relates to a carrier for a thin layer and a method for the analysis of molecular interactions on and/or in such a thin layer. A thin layer disposed on a carrier is illuminated with electromagnetic radiation from at least one radiation source and a reflected radiation part on boundary surfaces of the thin layer is detected by means of an optoelectronic converter that converts the detected radiation into a frequency- and intensity-dependant photocurrent. A reading voltage is applied to the optoelectronic converter. By changing the reading voltage, the spectral sensitivity of the optoelectronic converter is varied such that a substantially constant photocurrent is obtained. Alternatively or in addition to varying the spectral sensitivity by changing the reading voltage, the reflected radiation part is detected with an optoelectronic converter that is designed as a sensor layer in the carrier. The carrier is particularly characterized in that it comprises a substrate on which at least one sensor layer with optoelectronic properties is disposed.