(Invited) Dye-Sensitized Photo Rechargeable Battery for Indoor Applications

Abstract

Dye-Sensitized Solar Cells (DSSCs) have great potentials owing to their aesthetic colors, transparency and low cost. Furthermore, they are favorable for indoor system, because DSSCs have great power conversion efficiency (PCE) at low light. However, there are still several problems in the practical applications. Therefore, our group suggested the new concepts of organic materials and devices for approaching to real application. For this aim, we developed dye-sensitized photo rechargeable solar battery for indoor light saving.Until now, most of single-structured photo-rechargeable devices considered photo-charging process at high light intensity (mainly standard AM 1.5G sunlight). Furthermore, it is very difficult to combine dye-sensitized solar cells with lithium ion battery in a monolithic device because of their intrinsic mismatch energy levels of photo (-0.5 V vs NHE) and storage electrode (-3.0 V vs NHE). We came up with this intrinsic issues by using the overlithiation reaction of LiMn2O4 (ca. 0.0 V vs NHE) for energy storage and finally, achieved self-powered dye-sensitized photo rechargeable battery (DSPB, FTO/TiO2/Dye/Redox mediator/Pt-Li+ conducting separator/Li+ solution/ LixMn2O4) in monolithic devices, and suggested new concepts for energy recycle of indoor lightening. Next, we investigated the light intensity dependence of photo-charged energy density with different redox mediator (or charge regenerator for oxidized dye), such as I−/I3 −, Co2+/3+(bpy)3, Cu+/2+(dmp)2. Finally, the DSSBs were successfully working at low light intensity (11.5% of ηoverall at 0.15 mW cm−2 (500 lux)), operating the commercial IoT wireless sensor node using only indoor light sources.