and convert it to electricity. Nowadays, silicon-based solar cells are considered as the most matured PVSCs that possess a power conversion efficiency (PCE) over 25%. [2] However, silicon-based solar cells have several drawbacks including low flexibility, requirement of high purity silicon, and employment of energy-intensive process, thus cost-effective and ease-fabricated dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs) have become emerging candidates for solar energy harvesting with reported PCE as high as 14% and 25%, respectively. [3] Although PSCs have reached a remarkable PCE of 25% from lower than 10% just within a decade, [3g,4] the commercialization of PSCs could be hindered by the use of toxic lead-based materials for its excellent performance. [5] Accordingly, DSSCs have numerous advantages over their counterparts, for example, low cost of materials needed to fabricate DSSCs, mechanical robustness, transparency, and colorfulness. Furthermore, DSSCs have shown potential application as indoor photo voltaics (IPVs) to harvest energy from artificial light sources such as halogen lamps, fluorescent lamp, and light-emitting diode (LED) bulbs. [6] With the development of Internet of Things (IoT) in the coming decades, IPVs are important alternatives of batteries for billions of wireless sensors that work indoor or under dim-light conditions, [7] showing a great opportunity for DSSC applications. To enhance the PCE of DSSCs for indoor use, the light absorber undoubtedly is the most important component and should show absorption that matches well with the spectrum of light sources. In 2019, Venkatesan et al. reported quasi-solid-state DSSCs that exhibited a PCE as high as 20.63% under T5 fluorescent light illumination using benchmark ruthenium-based dye N719 as a sensitizer. [8] However, ruthenium-based dyes are not an ideal candidate for large-scale application due to expensiveness and rarity of ruthenium source on the earth. Thus ruthenium-free dyes including porphyrin-based and organic dyes that are composed of abundant elements including H, C, N, O, and S play a key role in the development of DSSCs for indoor and outdoor uses. The properties of ruthenium-free dyes such as HOMO/ LUMO energy levels, UV-vis absorption, and intra molecular charge separation can be readily tailored by molecular engineering, thus several design strategies for ruthenium-free New anthracene-bridged organic dyes CXC12 and CXC22 are designed and synthesized for high-efficiency dye-sensitized solar cells (DSSCs) under dim light. Compared to their parent dye TY6, CXC dyes have additional anthracene-acetylene group to extend the π-conjugation of the molecules, resulting in red-shifted absorption and an enhanced molar extinction coefficient. The absorption spectra of CXC12 and CXC22 with a maximum located at 561 and 487 nm, respectively, match to those of AM 1.5G sunlight and T5 fluorescent light better than that of TY6 (419 nm). It was initially anticipated that long alkoxyl chains introduced to the 2,6-positio...

No abstract