The Dawn of Single Material Organic Solar Cells

Abstract

Single material organic solar cells (SMOSCs) are based on ambivalent materials containing electron donor (D) and acceptor (A) units capable to ensure the basic functions of light absorption, exciton dissociation, and charge transport. Compared to bicomponent bulk heterojunctions, SMOSCs present several major advantages such as considerable simplification of cell fabrication and a strong stabilization of the morphology of the D/A interface, and thus of the cell lifetime. In addition to these technical issues, SMOSCs pose fundamental questions regarding the possible formation, and dissociation of excitons on the same molecular D–A architecture. SMOSCs are developed with various approaches, namely “double‐cable” polymers, block copolymers, oligomers, and molecules that differ by the donor platform: polymer or molecule, the nature of A, the D–A connection, and the intra‐ and intermolecular interactions of D and A. Although for several years the maximum efficiency of SMOSCs has remained limited to 1.0–1.5%, impressive progress has been recently accomplished leading to SMOSCs with 4.0–5.0% efficiency. Here, recent advances in the synthesis of D–A materials for SMOSCs are presented in the broader context of the chemistry of organic photovoltaic materials in order to discuss possible directions for future research.

Significantly Improved Morphology and Efficiency of Nonhalogenated Solvent‐Processed Solar Cells Derived from a Conjugated Donor–Acceptor Block Copolymer

“…Over the past two decades, several research groups, including our own, have been studying new materials that covalently anchor the electron donor (D) and acceptor (A) moieties . PSCs bearing above‐mentioned materials have recently been studied in two main forms.…”

Field Effect versus Driving Force: Charge Generation in Small‐Molecule Organic Solar Cells

“…[7,14] Single-component OSCs (SCOSCs) promise a simpler device fabrication and a potential solution to the morphological instability of many bulk heterojunction OSCs. [15] SCOSCs do not rely on charge separation at a heterojunction and vivid research has been performed to enhance in the efficiency of those systems by increasing their dielectric constant, exploiting bulk ionization effects or utilizing block copolymers that combine donor and acceptor moieties to facilitate the dissociation of excitons. [16][17][18] Among others, Chandran et al have reported the direct free carrier generation in SCOSCs employing the small molecule chloroboron subnaphthalocyanine (SubNc), which reached an EQE of 22% despite the absence of an acceptor molecule.…”

Crystalline Cooperativity of Donor and Acceptor Segments in Double‐Cable Conjugated Polymers toward Efficient Single‐Component Organic Solar Cells

“…Thed ouble-cable conjugated polymer is one of the most important material categories for single-component organic solar cells (SCOSCs), [1] in which the electron-accepting segments are covalently linked to the conjugated donor polymers to guarantee the intramolecular charge transfer from donor to acceptor.T his is an elegant approach to overcome the limitation of conventional bulk-heterojunction organic solar cells (BHJOSCs). First, the device fabrication process will be greatly simplified since the photoactive layer contains only one single material.…”