Amalie Dualeh

Tris(2-(1H-pyrazol-1-yl)pyridine)cobalt(III) as p-Type Dopant for Organic Semiconductors and Its Application in Highly Efficient Solid-State Dye-Sensitized Solar Cells

Chemical doping is an important strategy to alter the charge-transport properties of both molecular and polymeric organic semiconductors that find widespread application in organic electronic devices. We report on the use of a new class of Co(III) complexes as p-type dopants for triarylamine-based hole conductors such as spiro-MeOTAD and their application in solid-state dye-sensitized solar cells (ssDSCs). We show that the proposed compounds fulfill the requirements for this application and that the discussed strategy is promising for tuning the conductivity of spiro-MeOTAD in ssDSCs, without having to rely on the commonly employed photo-doping. By using a recently developed high molar extinction coefficient organic D-π-A sensitizer and p-doped spiro-MeOTAD as hole conductor, we achieved a record power conversion efficiency of 7.2%, measured under standard solar conditions (AM1.5G, 100 mW cm(-2)). We expect these promising new dopants to find widespread applications in organic electronics in general and photovoltaics in particular.

Impedance Spectroscopic Analysis of Lead Iodide Perovskite-Sensitized Solid-State Solar Cells

Mesoscopic solid-state solar cells based on the inorganic-organic hybrid perovskite CH3NH3PbI3 in conjunction with the amorphous organic semiconductor spiro-MeOTAD as a hole transport material (HTM) are investigated using impedance spectroscopy (IS). A model to interpret the frequency response of these devices is established by expanding and elaborating on the existing models used for the liquid and solid-state dye-sensitized solar cells. Furthermore, the influence of changing the additive concentrations of tert-butylpyridine and LiTFSI in the HTM and varying the HTM overlayer thickness on top of the sub-micrometer thick TiO2 on the extracted IS parameters is investigated. The internal electrical processes of such devices are studied and correlated with the overall device performance. In particular, the features in the IS responses that are attributed to the ionic and electronic transport properties of the perovskite material and manifest as a slow response at low frequency and an additional RC element at intermediate frequency, respectively, are explored.

A High-Efficiency Panchromatic Squaraine Sensitizer for Dye-Sensitized Solar Cells

Keywords: dyes/pigments ; light harvesting ; sensitizers ; solar cells ; squaraines ; Films Reference EPFL-ARTICLE-171211doi:10.1002/anie.201101362View record in Web of Science Record created on 2011-12-16, modified on 2017-12-03

Near-infrared sensitization of solid-state dye-sensitized solar cells with a squaraine dye

Here, we report the use of a squaraine-based dye, JD10, as a near-infrared sensitizer for solid-state dye-sensitized solar cells (ssDSCs). Using spiro-MeOTAD as a hole-transport material, JD10 gave the highest reported power conversion efficiencies (PCE), 3.16% for squaraine-based ssDSCs. The photocurrent was further enhanced by co-sensitization with the organic D-π-A dye D35, increasing the light harvested leading to a PCE to 4.42%.