Rational molecular engineering of porphyrins for enhanced performance in dye-sensitized solar cells

Abstract

Porphyrin dyes are promising sensitizers for high-efficiency dye-sensitized solar cells (DSSCs) due to their remarkable light-harvesting capabilities. However, realizing their full potential in photovoltaic devices necessitates meticulous optimization of their molecular structure. This study explores the structure–performance relationship in nine novel porphyrin dyes (TZ1–TZ9), aiming to enhance the overall power conversion efficiency (PCE). The impact of donor ability and its bulkiness is investigated using bis(4-hexylphenyl)amine and a bulky modified Hagfeldt donor (bis(2′,4′,6′-tris(hexyloxy)-[1,1′-biphenyl]-4-yl)amine). Indacenodithiophene IDT and thiophene groups are also incorporated as π-spacers to improve the light-harvesting efficiency and increase the overall molecular bulkiness. Furthermore, diverse acceptors (benzothiadiazole, benzotriazole, and cyanoacrylic acid) are introduced to fine-tune photophysical and electrochemical properties. Among these porphyrin dyes, TZ1 exhibits a remarkable PCE of 9.90% (short circuit photocurrent (J_SC) = 15.675 mA cm⁻², open circuit photovoltage (V_OC) = 0.834 V, and fill factor (FF) = 0.758), surpassing the PCE of 9.20% (J_SC = 14.737 mA cm⁻², V_OC = 0.817 V, and FF = 0.764) achieved by GY50 under similar fabrication conditions.