example of a suitable material the aforementioned application mentions tungsten oxide wo 3 the layer 14 is in turn covered with a compensating layer 16 which is in the form of a semi solid electrolyte including a transition metal oxide such as the compound titanium oxide tio 2 finally a counterelectrode layer 18 covers the compensating layer 16 and may be made from the element carbon a lead 20 is connected to the conducting electrode 12 while a second lead 22 is connected to the counterelectrode layer 18 when the device shown in fig1 is exposed to light in the direction illustrated there will be an immediate conversion of light energy to electrical energy and a voltage will be created between the leads 20 and 22 after some exposure to light charges will be stored in the charge storage layer 14 it is suspected that the charges become primarily produced in the compensating layer 16 while they are primarily stored in the charge storage layer 14 although the device illustrated in fig1 operates satisfactorily it is a relatively expensive device to fabricate further the charge storage layer 14 has a tendency to become colored after considerable exposure to light as a result the charge storage layer 14 acts as a filter and reduces the energy conversion capability of the device accordingly it is desirable to produce a cell of the type.