ABSTRACT
A molecular donor of intermediate dimensions based on dithienogermole (DTG) as the central electron rich unit, coded as DTG(FBT2Th2)2, was designed and synthesized for use in bulk heterojunction, solution-processed organic solar cells. Under optimized conditions, a maximum power conversion efficiency (PCE) of 9.1% can be achieved with [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) as the acceptor semiconductor component.
ABSTRACT
The molecule AT1, with two weakly conjugated chromophores, was designed, synthesized, and examined within the context of its film forming tendencies. While the addition of the second chromophore to the central core enables broadening of the absorption spectrum, this change is mostly apparent in films that are grown slowly. Grazing incidence X-ray scattering (GIWAXS) analysis indicates that these spectral characteristics correspond to an increase in solid state ordering. This information, in combination with differential scanning calorimetry, suggests that the overall molecular shape provides a kinetic barrier to crystallization. As a result, one finds the absence of molecular order when AT1 is combined with PC71BM in solution-cast blends. These findings highlight the importance of molecular topology when designing molecular components for solar cell devices.
ABSTRACT
Four new unsymmetric platinum(II) bis(aryleneethynylene) derivatives have been designed and synthesized, which showed good light-harvesting capabilities for application as photosensitizers in dye-sensitized solar cells (DSSCs). The absorption, electrochemical, time-dependent density functional theory (TD-DFT), impedance spectroscopic, and photovoltaic properties of these platinum(II)-based sensitizers have been fully characterized. The optical and TD-DFT studies show that the incorporation of a strongly electron-donating group significantly enhances the absorption abilities of the complexes. The maximum absorption wavelength of these four organometallic dyes can be tuned by various structural modifications of the triphenylamine and/or thiophene electron donor, improving the light absorption range up to 650 nm. The photovoltaic performance of these dyes as photosensitizers in mesoporous TiO(2) solar cells was investigated, and a power conversion efficiency as high as 1.57% was achieved, with an open-circuit voltage of 0.59 V, short-circuit current density of 3.63 mA cm(-2), and fill factor of 0.73 under simulated AM 1.5G solar illumination.
