Anthracene‐Bridged Sensitizers for Dye‐Sensitized Solar Cells with 37% Efficiency under Dim Light

Abstract

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...

Holistically Optimizing Charge Carrier Dynamics Enables High-Performance Dye-Sensitized Solar Cells and Photodetectors

“…Generally, the transmission line model was applied to fit the abovementioned EIS profiles, which could obtain the charge carrier recombination resistance (R CT ) at the photoanode/ dye/electrolyte interface. 6 It is noted that devices based on the Ti 3 C 2 T x /TiO 2 photoanode produce higher R CT than control ones in the range of applied voltage (Figures 5c and S18, Nyquist plots of DSSCs via applying a bias potential of 0.4 V; Table S2, resistances obtained from Nyquist plots of DSSCs via applying a bias potential of 0.4 V), which complies with the trend of V oc of the derived champion devices. 36 The enhanced R CT of devices based on the Ti 3 C 2 T x /TiO 2 photoanode is beneficial for suppressing charge carrier recombination, which is also confirmed by their prolonged electron lifetime (Figure 5d).…”

“…As shown in Figure a,b, the electrochemical impedance spectroscopy (EIS) of champion DSSCs based on the TiO 2 photoanode and Ti 3 C 2 T x /TiO 2 photoanode under different bias potentials under darkness was implemented. Generally, the transmission line model was applied to fit the abovementioned EIS profiles, which could obtain the charge carrier recombination resistance ( R CT ) at the photoanode/dye/electrolyte interface . It is noted that devices based on the Ti 3 C 2 T x /TiO 2 photoanode produce higher R CT than control ones in the range of applied voltage (Figures c and S18, Nyquist plots of DSSCs via applying a bias potential of 0.4 V; Table S2, resistances obtained from Nyquist plots of DSSCs via applying a bias potential of 0.4 V), which complies with the trend of V oc of the derived champion devices .…”

“…Up to now, the state-of-the-art power conversion efficiency (PCE) of DSSCs has surpassed 14% when measured under 100 mW/cm 2 . What is more, the PCE of DSSCs under artificial light sources can transcend 37%, which highly outperforms than its counterparts. , The appealing intrinsic features coupling with gradually increasing efficiency of DSSCs impart it a very attractive characteristic as a promising renewable energy technology especially as indoor photovoltaics for the internet of things (IoT).…”

Bulky 3D Structures of Dithienopyrrol Dye with Copper(II/I) Redox Mediator Enabling Efficient Solar Cells with an Open-Circuit Voltage of 1.13 V

“…Although DSCs have a lower PCE under standard AM1.5G conditions in comparison with xampleperovskite solar cells, − DSCs with a tunable color palette and diaphaneity are very suitable for commercial applications in building-integrated PV (BIPV) and niche products for electronic devices than crystalline silicon solar cells. − Recently, DSCs were proven to exhibit a remarkably impressive PCE of 37% under dim light, superior to crystalline silicon and other thin-film semiconductor PV technologies, showing promising potential for use in power sources to charge portable consumer electronics and sensors . In this regard, further exploration is clearly warranted to achieve enhanced efficiency and long-term stability for the commercial success of DSCs.…”

“…23−30 Recently, DSCs were proven to exhibit a remarkably impressive PCE of 37% under dim light, superior to crystalline silicon and other thinfilm semiconductor PV technologies, showing promising potential for use in power sources to charge portable consumer electronics and sensors. 31 In this regard, further exploration is clearly warranted to achieve enhanced efficiency and long-term stability for the commercial success of DSCs. Up to date, donor−acceptor (D−A)-type judiciously tailored photosensitizers have achieved high PCEs of over 12% in conjunction with the cobalt electrolyte.…”