New Solar Cell-Battery Hybrid Energy System: Integrating Organic Photovoltaics with Li-Ion and Na-Ion Technologies

A solar energy conversion system, an organic tandem solar cell, and an electrochemical energy storage system, an alkali metal-ion battery, were designed and implemented in an integrated hybrid photorechargeable battery for simultaneous energy conversion and storage. As a proof of concept, the integrated power pack was successfully realized in a three-terminal hybrid assembly featuring two negative and a joint positive electrode. The device can be directly charged upon illumination (photocharging) and discharged on the external load for many cycles. Aspects and requirements related to materials design, their specific properties, and the encapsulation issues are presented and discussed. Data on the compatibility of materials for solar cells with those used in batteries is presented for the first time. We also report on the efficiency of the solar cell part, the battery part, as well as the overall energy efficiency of the new system. From the behavior of this first of a kind device, we were able to derive its relevant characteristics that will guide future work in this highly application-oriented research field.