Synthesis Of Water-Soluble Non-Conjugated Polymers For Cathode Interfacial Modification In Polymer Solar Cells

Polymer solar cells(PSCs) have attracted considerable attention over the past decades due totheir unique characteristics, such as low cost, light weight, and possible flexibility andlarge-area printing. PSCs usually adopt a basic architecture composed of a thin layer oforganic semiconducting material sandwiched between two electrodes. It is therefore importantto control the properties and ohmic contact of the organic/electrode interface to maximizeperformance. A variety of charge transporting materials for modifying electrodes in PSCshave been explored. Amino-functionalized conjugated polymer electrolyte(CPE) haveexhibited wide applications owing to their excellent optoelectronic properties, orthogonalsolvent processibility, and outstanding interfacial modification functions. However, becauseCPEs typically require a delicate and complicated synthesis procedure, nonconjugatedpoly-electrolytes(NPE) equipped with charged ionic groups in their chemical structure maybe ideal cathode interfacial materials.The studies demonstrated in this thesis are the development of novel multifunctionalamino-functionalized water-soluble non-conjugated polymers by optimizing side chains. Thenovel amino-functionalized non-conjugated polymers were successfully applied as cathodeinterlayer in polymer solar cells.In chapter 2, a series of homopolymer(PDMC) with different molecular weights andcopolymer(P(AM/DMC)-1, P(AM/DMC)-2) with different monomer ratio was synthesizedand used as cathode interlayer for inverted PSCs. The PCE of the inverted PSC based onITO/PDMC/PCz-DOBT8:PC71BM/Mo O3/Ag reached 4.2%. Doping 5% Cs F in PDMC, thePCE was elevated to 5.25%, better than that of Zn O as the interlayer. It is supposed thatstrong electrostatic interactions between cationic groups of the NPE and anionic oxygen ionsof the Zn O surfaces would supply a uniform formation of strong dipoles across the interfacesand an intimate interfacial contact. Our results also indicated that a cationic homopolymercould show a better interfacial modification than copolymers.In chapter 3, we synthesized two kinds of mononer(DBB and DHB) with longer sidechains than DMC. Then two homopolymers(PDBB and PDHB) and two copolymers(P(AM/DBB) and P(AM/DHB)) were synthesized and utilized as cathode interlayers forinverted PSCs. It was found that the surface morphology on ITO became worse with theincreasing of the length of side chain, leading to a lower PCE at last.In chapter 4, we synthesized a new mononer(DMAPS) with zwitterionic group. A newhomopolymer(PDMAPS) and two copolymer(P(AM/DMAPS)-1 and P(AM/DMAPS)-2)with different monomer ratios were synthesized and utilized as cathode interfacial materialsfor inverted PSCs. Unfortunately, the zwitterionic polymers did not show ideal interfacemodification effects.