Solution-Processed Quantum-Dot Solar Cells

Abstract

Size-dependent optical and electrical properties, known as quantum size effect, can be observed when the size of a material decreases to the nanometer scale, close to its exciton Bohr radius. The size-dependent absorption spectra enable covering the spectral region ranging from the visible through near-infrared to the short-wave infrared. Therefore, quantum dots (QDs) have been studied as key building elements for solar cells, and photodetectors. This chapter presents some basic knowledge on the chemistry of QDs and optical and electrical properties of their assembly, which is necessary to understand QD solar cells (Sects. 40.1 and 40.2), and then describes various types of colloidal quantum dot (CQD) solar cells (Sect. 40.3). Among the different type solar cells, the heterojunction solar cells formed with CQDs and wide-bandgap semiconductors (Sect. 40.4), and quantum-dot-sensitized solar cells (Sect. 40.5) are explained separately. This chapter then presents some strategies for achieving ultrahigh efficiency (Sect. 40.6). Finally, as future prospects of CQD solar cells, some of the potentials unique to solution-processed solar cells are addressed (Sect. 40.7), which will not only expand the existing application area, but also create new applications that have no yet been possible. Section 40.7 also demonstrates the present state of the performance stability, which is essential in practical applications.