• Energy Research

A water-soluble organic redox couple (TT−/DTT) and new organic dyes (D45 and D51) have been developed for aqueous dye-sensitized solar cells (DSCs). An optimal efficiency of 3.5% was obtained using the D51 dye and an optimized electrolyte composition. The highest IPCE value obtained was 68% at 460 nm.

The cobalt site-modified polymer could significantly promote charge transfer and reduce charge recombination of hematite for light-driven water oxidation.

A heterojunction is the key junction for charge extraction in many thin film solar cell technologies. However, the structure and band alignment of the heterojunction in the operating device are often difficult to predict from calculations and, due to the complexity and narrow thickness of the interface, are difficult to measure directly. In this study, we demonstrate a technique for direct measurement of the band alignment and interfacial electric field variations of a fully functional lead halide perovskite solar cell structure under operating conditions using hard X-ray photoelectron spectroscopy (HAXPES). We describe the design considerations required in both the solar cell devices and the measurement setup and show results for the perovskite, hole transport, and gold layers at the back contact of the solar cell. For the investigated design, the HAXPES measurements suggest that 70% of the photovoltage was generated at this back contact, distributed rather equally between the hole transport material/gold interface and the perovskite/hole transport material interface. In addition, we were also able to reconstruct the band alignment at the back contact at equilibrium in the dark and at open circuit under illumination.

AbstractNovel cyanine dyes, in which a tetrahydroquinoline derivative is used as an electron donor and 1‐butyl‐5‐carboxy‐3, 3‐dimethyl‐indol‐1‐ium moiety is used as an electron acceptor and anchoring group, were designed and synthesized for application in dye‐sensitized solar cells. The photovoltaic performance of these solar cells depends markedly on the molecular structure of the dyes in terms of the n‐hexyl chains and the methoxyl unit. Retardation of charge recombination caused by the introduction of n‐hexyl chains resulted in an increase in electron lifetime. As a consequence, an improvement of open‐circuit photovoltage (Voc) was achieved. Also, the electron injection efficiencies were improved by the introduction of methoxyl moiety, which led to a higher short‐circuit photocurrent density (Jsc). The highest average efficiency of the sensitized devices (η) was 5.6 % (Jsc=13.3 mA cm−2, Voc=606 mV, and fill factor FF=69.1 %) under 100 mW cm−2 (AM 1.5G) solar irradiation. All of these dyes have very high absorption extinction coefficients and strong absorption in a relatively narrow spectrum range (500–650 nm), so one of our organic dyes was explored as a sensitizer in co‐sensitized solar cells in combination with the other two other existing organic dyes. Interestingly, a considerably improved photovoltaic performance of 8.2 % (Jsc=20.1 mA cm−2, Voc=597 mV, and FF=68.3 %) was achieved and the device showed a panchromatic response with a high incident photon‐to‐current conversion efficiency exceeding 85 % in the range of 400–700 nm.

The ultrafast excited-state relaxation dynamics of indolo[3,2-b]carbazole (ICZ) molecules were investigated in thin films and single crystals. In the ICZ film, singlet fission (SF) was directly obs ...

A low-cost spiro[fluorene-9,9′-xanthene]-based HTM termed X60 showed high PCEs of 7.30% in ssDSCs and 19.84% in PSCs under one sun, respectively.

The identification of an efficient and stable redox mediator is of paramount importance for commercialization of dye-sensitized solar cells (DSCs). Herein, we report a new class of copper complexes containing diamine-dipyridine tetradentate ligands (L1 = N, N'-dibenzyl- N, N'-bis(pyridin-2-ylmethyl)ethylenediamine; L2 = N, N'-dibenzyl- N, N'-bis(6-methylpyridin-2-ylmethyl)ethylenediamine) as redox mediators in DSCs. Devices constructed with [Cu(L2)]2+/+ redox couple afford an impressive power conversion efficiency (PCE) of 9.2% measured under simulated one sun irradiation (100 mW cm-2, AM 1.5G), which is among the top efficiencies reported thus far for DSCs with copper complex-based redox mediators. Remarkably, the excellent air, photo, and electrochemical stability of the [Cu(L2)]2+/+ complexes renders an outstanding long-term stability of the whole DSC device, maintaining ∼90% of the initial efficiency over 500 h under continuous full sun irradiation. This work unfolds a new platform for developing highly efficient and stable redox mediators for large-scale application of DSCs.

A ligand-modified catalyst, Ni(OH)2–TPA, is synthesized for efficient HMF oxidation, wherein the uncoordinated carboxylate functions as the proton relay center, enabling continuous HMF oxidation in a flowing system.

A thiol–ene polymer is employed to enlarge the Stokes shift of CuInS2/ZnS quantum dots for application in luminescent solar concentrators (LSCs), and a certified record power conversion efficiency of 1.36% (area of 29 × 29 cm2) was achieved.