[en] A new theory that explains the complete transit time, early afterpulse, charge, light emission and pulse shape behavior of photomultipliers (PMTs) is presented. It applies to all phototube sensors and was verified with a new photosensor analysis method using pulse fits. Based on these findings, an extensive review of PMT properties is given and the suitability of PMT series and 84 photosensor types for large liquid scintillator neutrino detectors was analyzed by measurements and literature research. Further, an optical module with a light concentrator optimizing the detector homogeneity was developed.