<i>meso</i>-Diphenylbacteriochlorins: Macrocyclic Dyes with Rare Colors for Dye-Sensitized Solar Cells

We herein report the synthesis, UV–vis absorption, fluorescence emission, and redox properties of three novel <i>meso-</i>diphenylbacteriochlorins. Significantly, we show that substituents at the meso-positions of an air-stable bacteriochlorin can be manipulated for the first time. With proper design, this allows tailor-made bacteriochlorins to exhibit suitable properties for a chosen application. As an example, photovoltaic properties of two such bacteriochlorins in dye-sensitized solar cells are investigated. The results show that the bacteriochlorin dyes outperform a reference porphyrin dye. Intriguingly, the anodes sensitized with the new dyes display rare colorsblue and pink

Dual Functionality of BODIPY Chromophore in Porphyrin-Sensitized Nanocrystalline Solar Cells

A new organic dye (BET) was synthesized and coadsorbed on TiO₂ nanoparticles to make mixed BET/porphyrin-sensitized solar cells (DSCs). The BET is a boron dipyrromethene compound with one benzoic acid group attached to the meso position for its binding to the TiO₂ nanoparticles and two ethyl groups in the 3 and 3′ positions of pyrrolic units to broaden its absorption. Two ethyl groups are in the cis position, as revealed by its single-crystal X-ray diffraction analysis. The BET exhibits strong absorption in the green light region with an absorption maximum at 528 nm in CH₂Cl₂, which is complementary to the absorption spectrum of porphyrin dyes. When the BET coadsorbs on the TiO₂ nanoparticles with porphyrin dyes (TMPZn and LD12), the power conversion efficiencies increase from 1.09% to 2.90% for TMPZn-sensitized solar cells and from 6.65% to 7.60% for LD12-sensitized solar cells, respectively. The IPCE of the devices in the green light region increases dramatically due to the cosensitizing effect of BET. The fluorescence of BET in solution is partially quenched and that of porphyrin is enhanced in the presence of BET dye, indicating an intermolecular energy transfer from BET to the porphyrin dyes. The direct electron injection from BET to the TiO₂ conduction band was rather poor; only negligible photocurrent was observed. Comparative studies of absorption spectra on the TiO₂ nanoparticle films and electrochemical impedance at the dye/TiO₂ interface also indicate that the BET is an excellent coadsorber to prevent the aggregation of porphyrin dyes. An intermolecular energy transfer model is proposed to account for the observed photovoltaic enhancement of the cosensitization system

Cost-Effective Anthryl Dyes for Dye-Sensitized Cells under One Sun and Dim Light

A series of anthracene-based organic dyes were prepared via cost-effective synthetic procedures for dye-sensitized cell application. UV–visible and fluorescent spectra, electrochemical properties, and photovoltaic performance of the dyes were studied. Under one sun (100 mW/cm²), the AN-3 small cell outperforms others in the series. Under a dim light condition, the AN-3 modules showed PCE comparable to that of the Z907 modules. After optimizing the synthetic procedure, we found that AN-3 can be manufactured at a fairly low price

Performance Characterization of Dye-Sensitized Photovoltaics under Indoor Lighting

Indoor utilization of emerging photovoltaics is promising; however, efficiency characterization under room lighting is challenging. We report the first round-robin interlaboratory study of performance measurement for dye-sensitized photovoltaics (cells and mini-modules) and one silicon solar cell under a fluorescent dim light. Among 15 research groups, the relative deviation in power conversion efficiency (PCE) of the samples reaches an unprecedented 152%. On the basis of the comprehensive results, the gap between photometry and radiometry measurements and the response of devices to the dim illumination are identified as critical obstacles to the correct PCE. Therefore, we use an illuminometer as a prime standard with a spectroradiometer to quantify the intensity of indoor lighting and adopt the reverse-biased current–voltage (<i>I</i>–<i>V</i>) characteristics as an indicator to qualify the <i>I</i>–<i>V</i> sampling time for dye-sensitized photovoltaics. The recommendations can brighten the prospects of emerging photovoltaics for indoor applications