Functional Nanocomposites, Block Copolymers, and Nanocrystals: from Synthesis, Self-Assembly to Application

Conjugated polymer–nanocrystals nanohybrids, capitalizing on the advantages peculiar to solution-processable conjugated polymers (CPs) in conjuncti on wi h the high electron mobility and tunable optical properties of inorganic nanocryst als (NCs), have attracted considerable attention to achieve high efficiency organi c photovoltaics at low cost. The most elegant approach to obtain CP-NC nanohybrids is to che mically tether CPs on the NC surface. In our study, semiconductor organic −inorganic nanocomposites were synthesized by directly grafting CP, poly(3-hexylthiophene ), onto cadmium selenide nanorod surface (i.e., preparing P3HT −CdSe NR nanocomposites). The direct grafting was accomplished by two coupling reactions: Heck coupling of vinyl-terminated P3HT with bromobenzylphosphonic acid functionalized CdSe NRs (i.e., BBPACdSe), and a newly developed catalyst-free click reaction of ethyny l-terminated P3HT with azide functionalized CdSe NRs. Such rationally designed nanocomposites possessed a well-defined interface between P3HT and CdSe NRs, thereby promoti ng the effective dispersion of CdSe NRs within the nanocomposites and facilitating thei r electronic interaction. This is the first study of directly placing conjugated copolymers in intimate contact with semiconductor NRs, dispensing with the need for ligand e xchange chemistry as in copious past work. These nanocomposites offer a maximum interfacial ar ea between the constituents for efficient exciton dissociation. As such, it repr esents a significant advance in rational design and fabrication of organic −i organic hybrid solar cells with improved power conversion efficiency. As one of the most typical film preparation methods, the Langumuir -Blodgett (LB) technology has been widely utilized to produce copolymer films with m onoor multi-