Crafting Semiconductor Organic-inorganic Nanocomposites Via Placing Conjugated Polymers in Intimate Contact with Nanocrystals for Hybrid Solar Cells

Recent advances in the synthesis and assembly of nanocrystals (NCs) provide unique opportunities to exploit NCs for the development of next generation organic/inorganic hybrid solar cells as one of the most promising alternatives to Si solar cells to deliver efficient energy conversion with inexpensive fabrication. Herein, we report two simple yet robust routes to conjugated polymer-quantum rod (CP-QR) nanocomposites, dispensing with the need for ligand exchange chemistry. In the first strategy CdSe QRs were passivated with bromobenzylphosphonic acid (BBPA) which not only induced elongated growth but also functionalized the CdSe QR surface, forming BBPA-CdSe QRs. Subsequently, P3HT-CdSe QRs were yielded by Heck coupling of vinyl-terminated P3HT with BBPA-CdSe QRs. The reduced insulating length of BBPA facilitated improved electron interaction between CP and QR, greatly promoting the potential of P3HT-CdSe QR nanocomposites for use in solar cells with enhanced performance. In the second strategy the alkyne–azide cycloaddition, which belongs to an emerging field of click chemistry, was utilized in the preparation of P3HT-CdSe QR nanocomposites. The aryl bromide of BBPA was converted into azide functional group, forming N₃-BPA-CdSe QRs. Subsequent catalyst-free Huisgen 1,3-dipolar cycloaddition between ethynyl-terminated P3HT and N₃-BPA-CdSe QRs successfully yielded intimate P3HT-CdSe QR nanocomposites without introducing any deleterious metallic impurity. The charge transfer occurred at the P3HT/CdSe QR interface and was confirmed by systematic UV-Vis absorption, photoluminescence (PL), and time-resolved PL studies. The nanocomposites made by the catalyst-free click reaction exhibited a faster charge transfer from P3HT to CdSe than those produced by Heck coupling.