Some Effects of the Electric Contact in Films of Electroluminescent ZnS:Cu,Cl

A low‐conductivity layer placed between a conducting electrode and a film of evaporated electroluminescent ZnS : Cu , Cl phosphor has a pronounced effect on the properties of the cell. The logarithm of the integrated brightness varies inversely as the voltage or as the square root of the voltage, or their combination, depending on the electric contact and on the conditions of excitation. Three brightness peaks may be obtained in each half cycle of alternating voltage, one substantially in phase, the other two delayed. The in‐phase brightness peak is accompanied by some rectification of current. The direction of greater current is determined by the nature of the contact and the conditions of excitation.