Phenanthrene‐Fused‐Quinoxaline as a Key Building Block for Highly Efficient and Stable Sensitizers in Copper‐Electrolyte‐Based Dye‐Sensitized Solar Cells

Abstract

Dye-sensitized solar cells (DSSCs) based on Cu II/I bipyridyl or phenanthroline complexes as redox shuttles have achieved very high open-circuit voltages (V OC , more than 1 V). However, their short-circuit photocurrent density (J SC ) has remained modest. Increasing the J SC is expected to extend the spectral response of sensitizers to the red or NIR region while maintaining efficient electron injection in the mesoscopic TiO 2 film and fast regeneration by the Cu I complex. Herein, we report two new D-A-p-A-featured sensitizers termed HY63 and HY64, which employ benzothiadiazole (BT) or phenanthrene-fused-quinoxaline (PFQ), respectively, as the auxiliary electron-withdrawing acceptor moiety. Despite their very similar energy levels and absorption onsets, HY64-based DSSCs outperform their HY63 counterparts, achieving a power conversion efficiency (PCE) of 12.5 %. PFQ is superior to BT in reducing charge recombination resulting in the near-quantitative collection of photogenerated charge carriers.

Solution-processed next generation thin film solar cells for indoor light applications

“…122 By employing Cu electrolytes, improved PCEs have been demonstrated under ambient light conditions as well as full sun illumination. 123 However, this manufacturing method of solid-state DSSCs by introducing Cubased electrolytes followed by electrolyte solvent evaporation seems impractical because it is not only expensive but also creates additional cell resistance. Printable electrolytes, which can be coated on the photoelectrode using a printing technique, can solve the issues and facilitate organic molecules or polymers, possessing semiconducting properties.…”

Copper Complexes as Alternative Redox Mediators in Dye-Sensitized Solar Cells

“…In the same year, Zhu, Grätzel and coworkers coupled the BP2 complexes with two new organic dyes [ 48 ]. The structure of these new molecules was a derivative of the well-known dye Y123 previously mentioned, which was among the most efficient and widely used sensitizers for copper-based DSSCs.…”

Theoretical and experimental insights into the properties of donor–σ–acceptor type derivatives of quinoxaline and methanone containing different donor moieties

“…For example, 2,3-diphenylquinoxaline based compounds exhibiting aggregation induced emission (AIE) were found to be efficient blue emitters useful for ratiometric gas sensors for detecting the presence of HCl and NH 3 vapours through conversion of emission from blue to yellow. 12 The additional substitution of quinoxaline with donor moieties resulted in acidochromic behaviour of AIE emitter that have application in white OLEDs. 9 When the aryl groups of quinoxaline compounds were replaced by triarylamino moieties, the photoluminescence quantum yields of solid samples increased up to 90% making such compounds good candidates for solar concentrators.…”

“…Quinoxaline is a nitrogen-containing heterocyclic aromatic compound formed by the fusion of benzene and pyrazine rings. 1–3 Such an N-type heterostructure has electron-withdrawing properties that can be efficiently used in the design of the structures of organic electroactive compounds for organic light emitting diodes (OLED), 4–6 pH sensors, 7–9 dye-sensitized solar cells (DSSC), 10–12 and luminescent solar concentrators. 13,14 The electron-deficient quinoxaline unit can be easily modified for the design of the structures of highly efficient functional materials for organic electronics.…”

“…The employment of the benzothiadiazole as an auxiliary acceptor moiety in quinoxaline-based compound was found to extend the spectral response of organic dyes for improving the performance of DSSCs with PCE values of 12.5%. 12 It was suggested that two acceptor moieties be fused for the tuning of emission wavelength from yellow to red. 15 The rigid planar quinoxaline–methanone constituent moieties and highly twisted phenoxazine structures induced high photoluminescence quantum yields of 61–88% in the solid state and extremely small singlet–triplet energy splitting.…”