Charge recombination losses in thiophene-substituted porphyrin dyesensitized solar cells

Abstract

<div> Two new porphyrins that incorporate thiophene substituents as spacers between the conjugated</div> <div> porphyrin core and the anchoring cyanoacrylate group have been synthesised. The two dyes differ in the</div> <div> number of thiophene bridges; porphyrin 1a has only one thiophene group and porphyrin 1b has two</div> <div> thiophene rings connected by a double bond. The measured light-to-energy conversion efficiencies in 1a</div> <div> and 1b were assessed using two different electrolytes, LP1 and LP2, which differ in the presence of tertbutyl</div> <div> pyridine in LP1. An efficiency of 6% under standard measurement conditions has been achieved for</div> <div> 1a &thorn; LP1. However, for porphyrin 1b the use of electrolyte LP1 led to lower efficiencies and a value of</div> <div> approximately 4% was obtained. The differences between the two types of solar cells and the electrolytes</div> <div> have been studied in-depth using photo-induced time-resolved techniques such as CE (Charge Extraction)</div> <div> and TPV (Transient PhotoVoltage).</div>