This Review summarizes recent progress in the development of polymer solar cells. It covers the scientific origins and basic properties of polymer solar cell technology, material requirements and device operation mechanisms, while also providing a synopsis of major achievements in the field over the past few years. Potential future developments and the applications of this technology are also briefly discussed.

Polymer solar cells

-phenylenevinylene)s L4. Fluorene-Based Conjugated Polymers L4.1. Fluorene-Based Copolymers ContainingElectron-Rich MoietiesM4.2. Fluorene-Based Copolymers ContainingElectron-Deﬁcient MoietiesN4.3. Fluorene-Based Copolymers ContainingPhosphorescent ComplexesQ5. Carbazole-Based Conjugated Polymers R5.1. Poly(2,7-carbazole)-Based Polymers R5.2. Indolo[3,2-

https://ir.nctu.edu.tw:443/bitstream/11536/6508/1/000271856900020.pdf

Synthesis of Conjugated Polymers for Organic Solar Cell Applications

Controlled/living radical polymerization: Features, developments, and perspectives

A review was presented to demonstrate a historical description of the synthesis of light-emitting conjugated polymers for applications in electroluminescent devices. Electroluminescence (EL) was first reported in poly(para-phenylene vinylene) (PPV) in 1990 and researchers continued to make significant efforts to develop conjugated materials as the active units in light-emitting devices (LED) to be used in display applications. Conjugated oligomers were used as luminescent materials and as models for conjugated polymers in the review. Oligomers were used to demonstrate a structure and property relationship to determine a key polymer property or to demonstrate a technique that was to be applied to polymers. The review focused on demonstrating the way polymer structures were made and the way their properties were controlled by intelligent and rational and synthetic design.

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

The optoelectronic properties of polymeric semiconductor materials can be utilized for the fabrication of organic electronic and photonic devices. When key structural requirements are met, these materials exhibit unique properties such as solution processability, large charge transporting capabilities, and/or broad optical absorption. In this review recent developments in the area of π-conjugated polymeric semiconductors for organic thin-film (or field-effect) transistors (OTFTs or OFETs) and bulk-heterojunction photovoltaic (or solar) cell (BHJ-OPV or OSC) applications are summarized and analyzed.

π-Conjugated Polymers for Organic Electronics and Photovoltaic Cell Applications†

The Grignard metathesis (GRIM) polymerization of 3-alkylthiophenes proceeds by a quasi-“living” chain growth mechanism, not by a step growth process. Kinetic studies of the Grignard metathesis polymerization of 2,5-dibromo-3-alkylthiophenes showed that the molecular weight of poly(3-alkylthiophenes) is a function of the molar ratio of the monomer to nickel initiator, and conducting polymers with predetermined molecular weights and relatively narrow molecular weight distributions (PDIs = 1.2−1.5) can be made. Sequential monomer addition resulted in new block copolymers containing different poly(3-alkylthiophene) segments.

/pdf/experimental-evidence-for-the-quasi-living-nature-of-the-4n8cgc3wy8.pdf

Experimental evidence for the quasi-living nature of the grignard metathesis method for the synthesis of regioregular poly(3-alkylthiophenes)

Poly(3-alkylthiophenes) are conducting polymers that have good solubility, environmental stability, and processability.1 The synthesis of regioregular polythiophenes has produced defect-free, structurally homogeneous, head-to-tail coupled poly(alkylthiophenes) (HT-PATs) that have greatly improved electronic and photonic properties over regiorandom analogues.2,3 Regioregular polythiophenes have led to a multitude of important and novel nanoand microscale electronic materials and devices.4-7 Very recently, we have developed an endgroup functionalization methodology of HT-PATs that allows for the synthesis of a plethora of well-defined block copolymers that form nanowires with high electrical conductivity.7 Here, we have discovered that the nickel-initiated regioregular polymerization of alkylthiophenes proceeds by a chain growth mechanism and does not occur by the accepted step growth mechanism.8 We also observed that the degree of polymerization of the synthesized poly(alkylthiophenes) increases with the conversion and can be predicted by the molar ratio of monomer to nickel initiator. On the basis of our experimental results, we predict that nickel-initiated crosscoupling polymerization is essentially a living system, giving PATs with low polydispersities (PDIs). In a cross-coupling step polymerization catalyzed by Ni(dppp)Cl2, one would expect a fast disappearance of the monomer and increase of the polymer molecular weight toward the end of the polymerization.8-10 On the basis of the experimental results, we observed that relatively high molecular weight polymer forms almost immediately. As a model reaction, we have also found that 2 equiv of a variety of aryl dibromides and 1 equiv of an aryl organometallic (either magnesium or zinc) always gives a near quantitative yield of the trimeric aryl and minor amounts ( 98% H-T coupling).12 The mechanism of the cross-coupling chaingrowth polymerization is outlined in Scheme 1. The first step in the mechanism, where the 2-bromo-5-chlorozinc3-hexylthiophene monomer (1) generated in situ from 2-bromo-3-hexylthiophene reacts with Ni(dppp)Cl2, yielding the organonickel compound (2), is as it has been described by others.9,13 We differ in our mechanism in that reductive elimination of 2 immediately forms an associated pair [3‚4] of the tail-to-tail aryl halide dimer (4) and nickel (0) (3). The dimer 4 undergoes fast oxidative addition to the nickel center generating 5, in view of the fact that the formation of the complex 3‚4 eliminates potential separation of 4 from 3. Subsequently, growth of the polymer chain occurs by insertion of one monomer at a time as shown in the reaction cycle (5 f 6 f [3‚7] f 5), where the Ni(dppp) moiety is always incorporated into polymer chain as an end group. Addition of various Grignard reagents (R′MgX) at the end of polymerization results in end-capping of HT* Corresponding author: e-mail rm5g@andrew.cmu.edu. Figure 1. Conversion (filled symbols) and logarithm of monomer concentration (open symbols) vs time plots for 2-bromo-3-hexylthiophene polymerization at different concentration of Ni(dppp)Cl2 initiator (23-25 °C); [M]0 ) 0.075 mol/ L: (9, 0) [M]0:[Ni(dppp)Cl2] ) 136:1; (b, O) [M]0:[Ni(dppp)Cl2] ) 57:1; (2, 4) [M]0:[Ni(dppp)Cl2] ) 49:1.

/pdf/chain-growth-mechanism-for-regioregular-nickel-initiated-32zax9qdsl.pdf

Chain Growth Mechanism for Regioregular Nickel-Initiated Cross-Coupling Polymerizations

Low polydispersity regioregular polythiophenes with number average molecular weights ranging from 2 to 13 kDa were cast under the same conditions from solution to form a series of field effect transistors (FETs). Tapping mode AFM and grazing incidence small-angle X-ray scattering revealed that in all cases the polymers formed regular nanofibrillar morphologies with the width of nanofibrils proportional to the weight average contour length of polymer chains, indicating that conjugated backbones were oriented perpendicular to the nanofibril axes. FET charge carrier mobilities exhibited exponential dependence on nanofibril width, pointing to the decisive role of extended conjugated pathways in charge transport.

Nanostructure Dependence of Field-Effect Mobility in Regioregular Poly(3-hexylthiophene) Thin Film Field Effect Transistors

http://www.chem.cmu.edu/groups/mccullough/publication/PDF%20files/mci-polymer-05.pdf

Regioregular poly(3-alkylthiophene) conducting block copolymers

Conducting Regioregular Polythiophene Block Copolymer Nanofibrils Synthesized by Reversible Addition Fragmentation Chain Transfer Polymerization (RAFT) and Nitroxide Mediated Polymerization (NMP)

Mihaela C. Iovu

Papers

Experimental evidence for the quasi-living nature of the grignard metathesis method for the synthesis of regioregular poly(3-alkylthiophenes)

Chain Growth Mechanism for Regioregular Nickel-Initiated Cross-Coupling Polymerizations

Nanostructure Dependence of Field-Effect Mobility in Regioregular Poly(3-hexylthiophene) Thin Film Field Effect Transistors

Regioregular poly(3-alkylthiophene) conducting block copolymers

Conducting Regioregular Polythiophene Block Copolymer Nanofibrils Synthesized by Reversible Addition Fragmentation Chain Transfer Polymerization (RAFT) and Nitroxide Mediated Polymerization (NMP)