A Broadly Absorbing Perylene Dye for Solid-State Dye-Sensitized Solar Cells

Abstract

We present a new perylene sensitizer, ID176, for dye-sensitized solar cells (DSCs). The dye has the capability for very high photocurrents due to strong absorption from 400 to over 700 nm. Photocurrents of up to 9 mA cm -2 were achieved in solid-state DSCs employing the hole conductor 2,2′7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-MeOTAD), with a conversion efficiency of 3.2%. In contrast, the sensitizer did not perform well in conjunction with liquid iodide/tri-iodide electrolytes, suggesting a difference in the injection and regeneration mechanisms in these two types of dye-sensitized solar cells.Dye-sensitized solar cells (DSCs) are the focus of much research due to their ability to convert sunlight to electricity at a low cost. 1 DSCs using a liquid electrolyte with the iodide/ tri-iodide redox couple have reached power conversion efficiencies of over 11%. 2 In comparison, solid-state DSCs (sDSCs) using the hole conductor 2,2′7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-MeOTAD) have reached efficiencies of 4-5% with dyes showing much higher conversion efficiencies in liquid electrolyte DSCs. 3-6 Device performances of sDSCs are best when thin TiO 2 films (∼2 µm) are used due to limitations in pore filling and losses during charge transport. With ruthenium dyes, this limits the light harvesting as they have relatively low extinction coefficients. In comparison, organic dyes have much higher extinction coefficients but often also narrower absorption spectra. 7 Thus, to improve efficiencies, organic dyes with high extinction coefficients over a large range of the solar spectrum are needed. Here, we present a new perylene sensitizer, ID176, which absorbs strongly from 400 to above 700 nm. Intriguingly, this dye works well in solidstate DSCs but not in liquid electrolyte ones.Perylene dyes are promising candidates for DSC applications due to ease of synthesis, high stability, and broad absorption spectra. 8 However, previously published perylenes with good efficiencies in DSCs 9-11 were bound to TiO 2 through ringopening of an anhydride group, resulting in a significant spectral blue shift of their absorption spectra upon attachment to TiO 2 . In this work, we have replaced the anhydride anchor with a carboxylic acid anchor attached to a perylene monoimide, resulting in ID176 (Figure 1). The HOMO orbital of ID176 is mainly located on the bis(phenylamine) donor, while the LUMO orbital is mainly located on the perylene core. Thus, light absorption in this dye leads to internal charge transfer from the donor to the extremely strong imide acceptor. Figure 2 shows the absorption spectrum of ID176 in dichloromethane (DCM) solution and on TiO 2 . In solution, two absorption bands can be seen, one centered at 590 nm and a sideband at 480 nm. According to time-dependent DFT calculations, these bands correspond to a transition from the HOMO to the LUMO and to a transition from the HOMO-1 to the LUMO, respectively. Upon adsorption to TiO 2 , only a slight blue shift in ...

In silico designing of power conversion efficient organic lead dyes for solar cells using todays innovative approaches to assure renewable energy for future

“…Additionally, the molecular structure of sensitizer can stabilize the dye and can provide a mean to control the interfacial behavior of electron transfer at TiO 2 /dye/electrolyte interface. 9,10 A substantial number of research techniques and computational tools have been employed already by different research groups to develop efficient sensitizers for the better power conversion efficiency (PCE) [11][12][13][14] than the existing ones. Pastore et al 3 reported ab initio approach to model different interface of DSSCs by DFT and TD-DFT.…”

“…12 Environment friendliness and ease of fabrication make the later more prominent in the scientific community. Though a variety of metal-free organic dyes such as arylamine, 17,18 perylenes, 13 and anthocyanin dyes 19 have been explored, arylamine organic dyes (AOD) have received enormous attention in the last decade because of their high molar absorption coefficient and tunable donor-acceptor moieties. 17,18 The optimal performance of the solar cell is directed by multifaceted interactions between the device components and their multiple possible combinations that are experimentally challenging to address.…”

Research and Development of Dye-Sensitized Solar Cells in the Center for Molecular Devices: From Molecules to Modules

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17] for details on m esoporous TiO 2 electrode preparation, dye synthesis, electrolyte preparation, solar cell assembly and solar cell characterization.…”

“…[9] A compelling result obtained within CMD research is that some perylene-based dyes performed much better in solid-state DSCs using spiro-MeOTAD than in standard iodide / triiodide electrolyte-based DSCs. [10] This can be attributed to the much faster regeneration kinetics observed in solid-state DSCs.…”

Functionalized pentacenes for dye-sensitized solar cells

“…Most organic sensitizers absorb light below 600 nm while reasonably efficient near-IR/IR dyes used in DSSCs are only occasionally seen in literature. [24][25][26][27][28][29] Pentacene chromophores, with potential absorption out to 750 nm, 30 could extend the window of performance for DSSCs, provided that there is efficient coupling between the acene and the inorganic matrix. We report here the synthesis of a series of pentacene dyes ( Fig.…”