› › Synthesis And Study Of New Small Molecules For Organic Photovoltaic Applications






Synthesis and Characterization of Novel Conjugated Polymers and Small Molecules for Photovoltaic Applications

Author : Robert James Thompson

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Page : 299 pages

File Size : 42,70 MB

Release : 2017

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This dissertation describes the synthesis and characterization of several novel conjugated polymers and small molecules for use in research on organic photovoltaics (i.e. polymer solar cells/organic solar cells). Chapter 1 is an introductory chapter that briefly introduces semiconducting polymers and gives a brief overview of their use in polymer solar cells. Chapter 2 describes the synthesis and characterization of the conjugated polyelectrolyte, poly{(4,4-bis(3'-(N-ethyl-N,N-dimethylammonio)propyl)cyclopenta[2,1-b:3,4-b']dithiophene)-2,6-diyl-alt-(thiophene-2,5-diyl)} bromide (PCT). Chapter 3 describes the synthesis and characterization of a series of conjugated polymers containing substituted dithieno[3,2-a:2',3'-c]phenazine monomer units, and also describes the fabrication and analysis of solar cells devices made from these materials. Chapter 4 describes the synthesis and characterization of a series of conjugated polymers and small molecules based on the condensation of various aromatic o-diamines with o-diketones to produce novel N-heteroacenes. Chapter 5 gives a brief review of the work reported in this dissertation and provides suggestions for future work that can be built on those findings.





Synthesis and Characterization of Conjugated Polymers and Small Molecules for Organic Photovoltaic Devices

Author : Obum Kwon

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Page : 134 pages

File Size : 41,3 MB

Release : 2013

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ISBN : 9781303539312

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Solar energy harvested directly from sunlight using photovoltaic (PV) technology has become one of the most promising ways to meet growing global energy needs with a sustainable resource while minimizing environmental concerns. Especially, organic bulk heterojunction (BHJ) solar cells have been attracting a great deal of interest as a source of renewable energy because of their potential as low-cost, flexible, light-weight and large-scale devices. The choice of materials in a BHJ solar cell is very important for device performance because the power conversion efficiencies (PCEs) are determined by their some crucial characteristics such as energy levels, charge transfer mobilities and structural orders. In this dissertation, two carbazole-diketopyrrolopyrrole based conjugated polymers (P1 and P2) and three thieno-[3,4-c]pyrrole-4,6-dione (TPD) based small molecules (M1, SM1 and SM2) were synthesized and characterized to investigate their optical, electrical and photovoltaic properties. First, the substitution of alkyl and aryl side chains on the carbazole moiety of two push-pull conjugated polymers (P1 and P2) shows the significant differences in the optical, electrical and photovoltaic properties. Second, TPD-based conjugated small molecule with a donor-acceptor-donor-acceptor-donor (D-A-D-A-D) framework, M1 shows the relatively deep HOMO level resulting the relatively high Voc.(0.85 eV) Small molecule BHJ solar cells were fabricated and characterized using different M1:PC71BM blend ratios, solvents, and additives and the highest PCE achieved in this study was 1.86%. Lastly, different bridgehead atoms of SM1 and SM2 can affect their energy band levels and device performances. The PCE (2.5%) of the SM2-based SM-BHJ solar cell was higher than that of the SM1-based SM-BHJ solar cell (1.5%).



Design and Synthesis of Small Molecules for Photo Voltaics

Author : Rafael Sandoval Torrientes

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Page : 240 pages

File Size : 23,33 MB

Release : 2017

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Introduction The current energetic regime, which relies on non-renewable polluting energy sources, is unsustainable from societal, economical, geopolitical, and environmental points of view. The only fully renewable source able to meet world’s huge and always growing energy demand is solar energy. Photovoltaic technologies, directly converting sunlight into electricity, represent one of the most promising candidates to meet this demand. Objectives Chapter 1: Development of new small molecules for organic solar cells (OSC). Chapter 2: Development of new small molecules as hole transporting materials (HTM) for perovskite solar cells. Results and Discussion Chapter 1. Small molecules for organic solar cells i) A−D−A Small molecules based on BDT-BTD Electroactive molecules featuring A−D−A architecture that employ some of the best performing electron donor and acceptor fragments found in the literature, namely benzodithiophene (BDT, as donor) and benzothiadiazole (BTD, as acceptor) have been designed and synthesized. Thiophene bridges of increasing length have been inserted in between A and D moieties (Figure S1a) in order to improve the absorption and aggregation properties. Optical, electrochemical and computational studies have revealed their electroactive nature and their ability to form well-ordered crystalline thin films. Photovoltaic devices employing these materials as donors in blends with fullerene derivatives showed poor performances, with best performing material (31) providing 0.72% PCE (Figure S1b)...



Design, Synthesis and Characterization of New Organic Semi-conductors for Photovoltaics

Author : Chunxiang Chen

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Page : 225 pages

File Size : 33,61 MB

Release : 2016

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Organic solar cells appear as a promising technology to meet future energy requirements, owing to their low production costs, their great flexibility and their ability to be integrated into light devices. Currently, they exhibit modest performances in photoconversion, thus new active molecules with optimized structural properties need to be developed. This work comes in that aim: on the basis of theoretical calculations with density functional theory, new organic semiconductors have been designed and synthesized. For this, the more economical and cleaner syntheses techniques have been employed. Thus, the coupling of the benzothiadiazole with thiophene carboxhaldehyde via direct heteroarylation without additive nor ligand is performed with success for the first time. According to green chemistry techniques, five molecules are thus isolated in only two steps. The study of their optical and electronic properties by means of different spectroscopic techniques (UV/vis, fluorescence) and electrochemistry, of their thermal properties, and of their ability to self-organize have revealed their promising abilities for use in organic photovoltaics. A series of small molecules based on dithienosilole (DTS) core have also been designed via DFT computations. The calculations show their considerable low bandgap. Their syntheses have been conducted. It anticipates their promising potential for organic photovoltaic applications. Finally, a purely theoretical work has been completed on molecules derived from boron subphthalocyanines. The calculations predict interesting electronic properties for these new materials that may lead to promising performances in organic photovoltaics, paving the way for innovative materials.