Molecular Engineering of Organic Dyes with a Hole‐Extending Donor Tail for Efficient All‐Solid‐State Dye‐Sensitized Solar Cells

Abstract

We report a new concept for the design of metal-free organic dyes (OD5-OD9) with an extended donor-π-acceptor (D-π-A) molecular framework, in which the donor terminal unit is attached by a hole-extending side chain to retard back electron transfer and charge recombination; the π-bridge component contains varied thiophene-based substituents to enhance the light-harvesting ability of the device. The best dye (OD9) has a D-A-π-A configuration with the hexyloxyphenylthiophene (HPT) side chain as a hole-extension component and a benzothiadiazole (BTD) internal acceptor as a π-extension component. The co-sensitization of OD9 with the new porphyrin dye LW24 enhanced the light-harvesting ability to 800 nm; thus, a power conversion efficiency 5.5 % was achieved. Photoinduced absorption (PIA) and transient absorption spectral (TAS) techniques were applied to account for the observed trend of the open-circuit voltage (VOC ) of the devices. This work provides insights into the molecular design, photovoltaic performance, and kinetics of charge recombination.

Advances in nanostructured thin film materials for solar cell applications

“…In the thin films SS-DSSC, TiO 2 is normally deposited on conducting transparent glass as an electrode in the solar cell , generally using "doctor blading" method [89]. Recent advances in the photovoltaic performance of the SS-DSSC have augmented the power conversion efficiencies from the initial 0.74% [94], to in the range of about 5-7% [95][96][97][98].…”

Molecular Engineering of Potent Sensitizers for Very Efficient Light Harvesting in Thin-Film Solid-State Dye-Sensitized Solar Cells

“…[11][12][13] This is particularly important in the case of dye regeneration and charge recombination processes at the TiO2/dye/HTM interface, where molecular-level modifications of organic sensitizers are employed as an effective approach to impede undesirable charge recombination processes. [13][14][15] This is exemplified in the case of Y123 ( Figure 1) and LEG4, featuring bulky donors and cyclopentadithiophene (CPDT)-based π-bridges, protected by alkoxy and alkyl chains, respectively. These bulky side chains shield the dye from the oxidized HTM and thereby inhibit recombination at the interface of TiO2/dye/HTM, leading to highly efficient ssDSSCs with spiro-OMeTAD.…”

Weakly Conjugated Hybrid Zinc Porphyrin Sensitizers for Solid‐State Dye‐Sensitized Solar Cells

“…It showed a PCE of 4.8%, which is the highest efficiency obtained for solid‐state DSCs while using a porphyrin dye until now . Quite recently, another porphyrin dye LW24 with dimethylaniline as a donor part, and benzothiadiazole‐benzoic acid unit as an acceptor part was shown by Diau and co‐workers . The dye LW24 gave a PCE of 3.0%.…”