Importance of Compact Blocking Layers to the Performance of Dye-Sensitized Solar Cells under Ambient Light Conditions

Abstract

Power generation in indoor environments is the next step in dye-sensitized solar cell (DSSC) evolution. To achieve this goal, a critical recombination route which is usually inhibited by the TiCl4-derived blocking layers (BLs), that is, charge transfer at the fluorine-doped tin oxide substrate/electrolyte interface, is of concern. In this study, we demonstrate that because of low surface coverage, the conventional TiCl4 BLs are unable to suppress such electron leakage, thus limiting the photovoltaic performance of Co­(bpy)3 2+/3+-mediated DSSCs (bpy = 2,2′-bipyridine) under ambient lighting. On the other hand, by introducing compact BLs prepared by spray pyrolysis, the DSSCs show lower dark current and operate efficiently not only under high-intensity sunlight but also under ambient light conditions. The better blocking function of the compact BL is verified by the cyclic voltammetry; other thin-film preparation methods, except for the common TiCl4 treatment, are anticipated to realize a similar blocking effect. This study illustrates that dense thin film with a predominant blocking function is highly required as the BL for DSSCs under low-light conditions, and this concept will pave the way for more development of indoor DSSCs.

Assessment of TiO2 Blocking Layers for CuII/I-Electrolyte Dye-Sensitized Solar Cells by Electrochemical Impedance Spectroscopy

“…This is a direct confirmation of Liu et al’s study, who demonstrated how chemical bath deposition, rather than coating a dense thin layer onto the electrode, leads to island-like crystal growth. 28 In return, the area of exposed FTO substrate remains the dominating electrode/electrolyte interface. Their study highlighted the detrimental effect this has on recombination and therefore performance of the DSCs under ambient light, which is here underlined.…”

Electrochemical Characterization of CuSCN Hole-Extracting Thin Films for Perovskite Photovoltaics

“…3−/4− . 12,13,44,45 Earlier SEM studies confirmed that our CuSCN films were perfectly uniform on the perovskite surface, while the films of alternative hole conductors (spiro-OMeTAD) contained pinholes. 7 To test this finding more quantitatively, we developed here an electrochemical method for the testing of blocking quality of CuSCN.…”

Indoor photovoltaics, The Next Big Trend in solution‐processed solar cells

“…Liu et al investigated the effect of different TiO 2 as a blocking layer on DSSCs performance. They found the sprayed compact TiO 2 enable DSSCs to obtain outstanding PCE efficiencies of 15.26% and 15.12% under low light intensities of 1001 and 250 lux, much higher than 8.56% and 6.19% in the reference cells 33 . Moreover, replacing the conventional liquid electrolyte with solid‐state electrolyte facilitates the improvement in performance of indoor DSSCs.…”

“…They found the sprayed compact TiO 2 enable DSSCs to obtain outstanding PCE efficiencies of 15.26% and 15.12% under low light intensities of 1001 and 250 lux, much higher than 8.56% and 6.19% in the reference cells. 33 Moreover, replacing the conventional liquid electrolyte with solid-state electrolyte facilitates the improvement in performance of indoor DSSCs. As reported recently, PCE of 15.39% and 20.63% were achieved with quasi-solid-state electrolyte under low light intensities of 200 and 600 lux, respectively.…”