Byung-Man Kim1 Myeong-Hee Lee1 Hyun-Kon Song1 Tae-hyuk Kwon1

1, Ulsan National Institute of Science and Technology, Ulsan, , Korea (the Republic of)

Dye-sensitized solar cells (DSCs) have been often used as photo-energy converter in hybrid rechargeable system because of their several advantages, especially sensitivity to light intensity. Nevertheless, the influential factors for the performance of DSC-combined energy storage devices are still veiled. In this work, we designed 3-electrode photo-energy conversion/storage system including dye-sensitized TiO2 photo-electrode, functionalized membrane electrode, and LiMn2O4 storage-electrode, as named dye-sensitized solar battery (DSSB). Three kinds of redox mediators, such as I/I3, Co+2/+3(bpy)3, and Cu+/+2(dmp)2 were introduced as charge regenerator for oxidized dye in order to investigate their impacts on the photo-energy conversion/storage performance of DSSB. As a result, I/I3 showing the highest photo-injection current generally provided the highest photo-charging current (JCh) and thus total stored energy (Estored) under one sun condition (1000 W m−2), followed by Co+2/+3(bpy)3 and Cu+/+2(dmp)2. However, under dim lighting (2.4 W m2), Cu+/+2(dmp)2 showed the highest Estored corresponding to 6.2% of photo-energy conversion/storage efficiency (ηoverall). The trend of ηoverall under dim lighting indicates that output voltage gradually becomes influential for Estored as the incident light intensity decreases, while the impact of JCh becomes negligible. These findings present which factors we should consider to develop the DSSBs suitable for indoor application.