A method for delivering encrypted content to a subscriber terminal on-demand through a communication network is provided. The invention requires three chemicals CO2, Ca2, and sodium chloride NaCl to produce NaHCO3. Preferred examples of the proton acceptor include a salt structure composed of an anion and a cation derived from a basic organic compound, a basic organic compound, and a dissociation-facilitating polymer which facilitates dissociation of proton. The photoconductive switch module further comprises a third substrate arranged between the first substrate and the second substrate.