Carbazole-Based Organic Dyes for Solar Cells

Next-generation organic photovoltaic cells (OPVs) offer a flexible, lightweight, inexpensive, fine-tuned physicochemical, charge-transporting, and device parameter alternative to silicon-based solar cells (Si-SCs). Polyaromatic hydrocarbons (PAHs) permit fine-tuning of physicochemical, charge-transporting, and device properties, making them desirable organic functionalization methods. Significant solar material and technological advancements have occurred over the past two decades. Due to their well-defined molecular structure, molecular weight, and exceptional purity with no batch-to-batch variation, small-molecule-based semiconductors for OPVs are gaining popularity. Among heteroatom-containing PAHs, carbazole (Cbz) is one of the most promising organic electronics building blocks, particularly OLEDs and OPVs, due to its excellent hole-transporting competence, outstanding thermal and morphological order, polymorphic nature, inexpensiveness, significant triplet energy, and functionalization versatility. Cbz-based functional materials (C3, C6-, or C2, C7-, or N-) are frequently derived in organic solar cell construction due to their high electron content; they are a donor, auxiliary donor, or connecting spacer between donors and acceptors. Recent interest has been drawn to fused Cbz donors or Cbz-polyfunctionalization at various locations because decreasing the bandgap can avoid charge density development and increase solar light collection. This chapter discusses the chemical structures of molecules as they relate to energy levels, charge mobilities, absorption, and photovoltaic efficiency (PVE). An in-depth understanding of the structure-property relationship may aid the exploration and rational design of Cbz-based solar materials.