Article pubs.acs.org/JPCC
Organic Dyes with Hydrazone Moieties: A Study of Correlation between Structure and Performance in the Solid-State DyeSensitized Solar Cells Simona Urnikaite,† Tadas Malinauskas,† Ingmar Bruder,*,‡ Robert Send,‡ Valentas Gaidelis,§ Rüdiger Sens,‡ and Vytautas Getautis*,† †
Department of Organic Chemistry, Kaunas University of Technology, Radvilenu pl. 19, Kaunas 50254, Lithuania BASF SE, Carl-Bosch-Strasse 38, Ludwigshafen 67056, Germany § Department of Solid State Electronics, Vilnius University, Sauletekio 9, Vilnius 10222, Lithuania ‡
S Supporting Information *
ABSTRACT: New metal-free organic dyes for solid-state dye-sensitized solar cells, employing a hydrazone fragment, have been synthesized and investigated. These sensitizers are obtained from relatively cheap starting materials, without the use of expensive catalysts, rigorously anhydrous or oxygen-free conditions. Correlation between the structure of hydrazone-containing dyes and the performance of the solidstate DSSC is investigated. The highest obtained solid-state device conversion efficiency, under standard AM 1.5G illumination (100 mW cm−2), was 4.5% (JSC = 8.03 mA cm−2, VOC = 880 mV, FF = 0.64).
1. INTRODUCTION Dye-sensitized solar cells (DSSCs) have attracted significant attention as an appealing alternative to conventional semiconductor photovoltaic devices,1,2 promising to offer a solution to low-cost large-area photovoltaic applications. DSSCs are fabricated from cheap, easily processable materials, deriving their competitive performance from judicious molecular design and control of nanoarchitecture. Ruthenium complexes as molecular sensitizers have shown impressive solar-to-electric power conversion efficiencies (PCE) in liquid electrolyte-based devices, with the PCE reaching over 11% under standard AM1.5G full sunlight.3−7 Another type of sensitizer that demonstrated impressive performance in liquid electrolyte-based devices is dyes based on porphyrin zinc complex. Porphyrin-sensitized DSSC with cobalt(II/III)-based redox electrolyte achieved near 13% efficiency.8 However, the disadvantages of liquid electrolytebased DSSCs, such as solvent evaporation and leakage as well as the corrosive and photochemical properties of iodine, are strong driving forces in the search for alternatives. One of the possible solutions could be solid-state DSSCs (ssDSSCs).9,10 In ssDSSCs a solid hole-transporting material (HTM) could be employed to replace the liquid redox electrolyte which is responsible for dye regeneration and hole transfer to the counter electrode. Due to insufficient conductivity of solid organic HTMs, the ssDSSCs are currently restricted to using
