Although the conversion efficiency is impressive, the expense of the dye required to sensitize the solar cell is still not feasible for practical applications. Therefore, it is critical to tailor the materials to be not only cost effective but also long lasting. Recently, the utilization of narrow-bandgap 4SC-202 cost semiconductors as a light-absorbing material, in place of conventional dye molecules,
has drawn much attention. Inorganic semiconductors have several advantages over conventional dyes: (1) The bandgap of semiconductor nanoparticles can be easily tuned by size over a wide range to match the solar spectrum. (2) Their large intrinsic dipole moments can lead to rapid charge see more separation and large extinction coefficient, which is known to reduce the dark current and increase the
overall efficiency. (3) In addition, semiconductor sensitizers provide new chances to utilize hot electrons to generate multiple charge carriers with a single photon. These properties make such inorganic narrow-bandgap semiconductors extremely attractive as materials for photovoltaic applications. Recently, a range of nano-sized semiconductors has been investigated in photovoltaic applications including CdS [7–9], CdSe [10–13], Ag2S [14], In2S3[15], PbS [16], Sb2S3[17], Cu2O [18], as well as III-VI quantum ring [19]. Among these narrow-bandgap semiconductors, 4-Aminobutyrate aminotransferase Sb2S3 has shown much promise as an impressive sensitizer due to
its reasonable bandgap of about 1.7 eV, exhibiting a strong absorption of BAY 80-6946 in vivo the solar spectrum. The use of Sb2S3 nanoparticles, which may produce more than one electron–hole pair per single absorbed photon (also known as multiple exciton generation), is a promising solution to enhance power conversion efficiency. Furthermore, the creation of a type-II heterojunction by growing Sb2S3 nanoparticles on the TiO2 surface greatly enhances charge separation. All of these effects are known to increase the exciton concentration, lifetime of hot electrons, and therefore, the performance of sensitized solar cells. Limited research has previously been carried out with Sb2S3-TiO2 nanostructure for solar cell applications [20–22]. A remarkable performance was obtained in both liquid cell configuration and solid configuration. These findings were based on the use of porous nanocrystalline TiO2 particles; however, very little research has been conducted using single-crystalline TiO2 nanorod arrays. Compared with conventional porous polycrystalline TiO2 films, single-crystalline TiO2 nanorods grown directly on transparent conductive oxide electrodes provide an ideal alternative solution by avoiding particle-to-particle hopping that occurs in polycrystalline films, thereby increasing the photocurrent efficiency.