Abstract

Organic photovoltaics (OPV) offer great promise as a low-cost renewable energy source, the relative low efficiency still challenges its commercialization potential. Small conjugated molecules like Squaraine (SQ) molecules show promising advancement in organic photovoltaics (OPV). Advantages of SQ over other materials is that it has a high extinction coefficient (>10^5), decent photo-stability, good synthetic reproducibility, and tunable molecular structure. With small chemical modifications, the squaraines can have substantial impact on photophysical properties and aggregation pattern, and thus on operational OPV efficiency. The squaraine molecule that will be studied in this work is a symmetric aniline-based squaraine with n-hexyl chain on the molecular arm with di hydroxyl substituents on the aniline, this will be referred to DHSQ(OH)2. In this work, the assignment of the monomer and aggregate peak is discussed. It is known that crystallinity is important for efficient charge transport and exciton diffusion in the BHJ, this thesis focuses on thermal and solvent vapor annealing the as-cast films to reduce the amorphous regions. It is observed that crystallinity is improved but often at the expense of larger crystal size. Therefore, to achieve optimal OPV efficiency, this tradeoff is controlled to improve the crystallinity while maintaining a small, highly mixed BHJ morphology.

Publication Date

7-2017

Document Type

Thesis

Student Type

Graduate

Degree Name

Chemistry (MS)

Department, Program, or Center

School of Chemistry and Materials Science (COS)

Advisor

Christopher Collison

Advisor/Committee Member

Jeremy Cody

Advisor/Committee Member

Nathan Eddingsaas

Campus

RIT – Main Campus

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