Application of Fluorescence Resonance Energy Transfer in Dye-Sensitized Solar Cells

• Main Authors: Yu-Jie Lin, 林裕傑
• Other Authors: Chih-Ming Chen
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/37807802504354797941

博士 === 國立中興大學 === 化學工程學系所 === 105 === This dissertation investigates the application of the fluorescence resonance energy transfer (FRET) effect induced by an organic fluorophores (1,8-naphthalimide derivative) in dye-sensitized solar cell (DSSC). There are two parts of research in this dissertation based on two organic fluorophores with and without a carboxylic group. In Part I, an organic fluorophore without a carboxylic group, named as N-Bu, is doped into a mesoporous TiO2 photoanode by a two-step dipping procedure sequentially in the N-Bu and N719 solutions. The N-Bu fluorophore can be excited via absorbing ultraviolet light and then transfers the absorbed energy to the N719 sensitizing dye by means of the FRET effect when the N-Bu and N719 molecules are within the Förster radius. The high spectral overlap between the emission spectrum of fluorophore and the absorption spectrum of sensitizing dye is also advantageous for the FRET effect. Therefore, the FRET effect promotes the light harvesting of DSSC in the ultraviolet spectrum range and the incident photon to current conversion efficiencies (IPCE). An improved power conversion efficiency (PCE) of 8.13% is obtained for the fluorophore-doped (10-4 M) DSSC as compared with that without the doping of fluorophore (7.63%). In Part II, a 1,8-naphthalimide derivative with a carboxylic group, N-COOH, is doped into a mesoporous TiO2 film together with N719 by a co-adsorption method which is performed by dipping the mesoporous TiO2 photoanodes into the mixed solutions of N719 and N-Bu. The photobehavior of N-COOH is similar to the N-Bu fluorophore which is used in the Part I. Hence, the N-COOH fluorophore can also absorb the ultraviolet light and transit the absorbed energy to N719 by means of FRET. Because the N-COOH fluorophore can adsorb on the TiO2 surface with its carboxylic group as N719 does, an in-situ FRET system can be built up to induce more efficient energy transfer from the FRET donor (N-COOH) to the FRET acceptor (N719). The co-adsorption of N-COOH with N719 does not influence the dye-loading amount of N719 in the mesoporous TiO2 film, and it can further inhibit charge recombination owing to reduced contact area between TiO2 and electrolyte. The results show that the DSSCs with doping of the N-COOH fluorophore are efficient for 1 sun (AM1.5G) and indoor lighting conditions. Upon using optimal mixed solution (N719:N-COOH = 5:1), the PCE of DSSC under 1 sun illumination increases by 10.8 % (from 9.16 to 10.15 %), and that for T5 fluorescent lamps of 600 lux increases by 21 % (PCE from 16.46 to 19.92 % and Pmax from 31.77 to 38.44 μW/cm2), as compared with that adsorbing N719 only.