Читать книгу Fundamentals of Solar Cell Design - Rajender Boddula - Страница 24

The chapter illustrates polymer donor and non-fullerene small-molecule acceptor and all small-molecule (donor and acceptor) BHJSC’s performance. It is evident from the examples cited that non-fullerene–based BHJOSCs are becoming increasingly popular and in particular all small molecule–based BHJOSCs have just started their journey and will take off further. We can say that fullerene-based BHJOSCs are becoming outdated due to their limitations and solar cell efficiency. Several examples cited in this chapter provide over 17% efficiency achieved for polymer donor and non-fullerene small-molecule acceptor and over 14% efficiency cited for all small-molecule (donor and acceptor) BHJSCs. It becomes clear that a variety of designs have been developed to make small molecules in order to test them for solar cell efficiency. It is predicted that these small-molecule BHJOSCs are expected to display higher efficiency in near future by the use of proper design of molecules and solar cell fabrications. More interestingly, all small-molecule (acceptor and donor) materials have higher advantage than polymer donor and small-molecule acceptor type solar cells. All small-molecule (acceptor and donor) design and synthesis is less expensive, and higher purity can be achieved. Their optical, thermal, and electrochemical properties are tunable by proper design of molecules. Most of the examples discussed in this chapter are not clear with stereochemistry of the terminal double bond attaching to electron withdrawing group (like rhodanine or indanone), since the E and Z isomers differ in their properties. Particularly, their dipolemoment (vector) or polarizability (tensor) may have an impact on the molecular association in the formation of films. Hence, defining the stereochemistry of double bond will improve solar cell functioning. The film morphology can be controlled by applying supramolecular chemistry interactions, while designing the small molecules. The thermal stability and photo stability coupled with high PCE will place these BHJOSCs for the possible commercial applications in the near future.