Advancing panchromatic effect for efficient sensitization of cyanine and hemicyanine-based dye-sensitized solar cells

Global warming and rising energy needs have prompted a renewed interest in alternative energy technologies. In recent years, dye-sensitized solar cells have gained substantial interest due to their potential for inexpensive photovoltaic energy conversion. Among variable organic photosensitizers, those based on cyanine (Cy) and hemicyanine (HCy) are notable for their stability and high molar absorption coefficients in the visible to near infrared spectral range. This article focuses on the most up-to-date advances and methods used in the structural design and synthetic approaches of Cy and HCy-based photosensitizers. The photophysical characteristics, photovoltaic parameters, and solar cell performances of their simple and advanced molecular structure engineering are discussed. The review also included recent strategies of utilizing Cy and HCy in solar cells as co-sensitizers or as part of the tandem devices to extend the panchromatic response. Hence, establishing a solid correlation between the structural design of Cy and HCy sensitizers, their panchromatic responses, and their conversion efficiencies would greatly help optimize new dyes to produce photovoltaic cells with efficient solar-energy conversion.