Enhancement of p-Type Dye-Sensitized Solar Cell Performance by Supramolecular Assembly of Electron Donor and Acceptor

Abstract

Supramolecular interactions based on porphyrin and fullerene derivatives were successfully adopted to improve the photovoltaic performance of p-type dye-sensitized solar cells (DSCs). Photoelectron spectroscopy (PES) measurements suggest a change in binding configuration of ZnTCPP after co-sensitization with C60PPy, which could be ascribed to supramolecular interaction between ZnTCPP and C60PPy. The performance of the ZnTCPP/C60PPy-based p-type DSC has been increased by a factor of 4 in comparison with the DSC with the ZnTCPP alone. At 560 nm, the IPCE value of DSCs based on ZnTCPP/ C60PPy was a factor of 10 greater than that generated by ZnTCPP-based DSCs. The influence of different electrolytes on charge extraction and electron lifetime was investigated and showed that the enhanced V oc from the Co 21/31 (dtbp) 3 -based device is due to the positive E F shift of NiO. P-type dye-sensitized solar cells (DSCs) 1-10 have attracted intensive interest in the community due to the potential applications in tandem devices 11,12 with n-type DSCs 13 as well as in the artificial photosynthesis systems 14,15 . So far, the highest efficiency of p-type dye-sensitized solar cells is 1.3% obtained by the combination between an organic dye and a cobalt redox couple 16 . In DSCs, the photosensitizer is always one of the crucial components of the devices. To date, some organic as well as inorganic photosensitizers have been developed for p-type DSCs [2][3][4][5]12,[17][18][19][20][21] . In order to improve the photovoltaic properties of p-type DSCs, the recombination process between injected holes in the valence band (VB) of the p-type semiconductor and reduced photosensitizer should be inhibited as much as possible 4 . This problem can be addressed by judicious design of the photosensitizer, including extension of the conjugated system to increase the distance between the electron acceptor unit and the p-type semiconductor surface. This synthetic approach has been shown to provide a longer lifetime of the charge separated state 12,22 . Recently, a porphyrin dye showed a promising device efficiency up to 11%, a comparable efficiency to classic Ru photosensitizers that are ubiquitous in n-type DSC 23. These two points were the main motivations for using porphyrin dyes in p-type DSCs. Lindquist and co-workers adopted the mesotetra(carboxyphenyl) porphyrin (TCPP) for p-type DSCs in 1999 24 . However, at that moment the efficiency of the p-type DSCs based on this porphyrin dye was very unsatisfying, around 0.003%, with the highest incident photon-to-current conversion efficiency (IPCE) value of 0.24% at 540 nm. The poor photovoltaic properties were probably due to the fast hole recombination processes and the quality of the NiO films. Inspired by previous examples of supramolecular interaction between porphyrin and C60 and the fast charge transfer process from porphyrin to C60 derivatives [25][26][27][28][29] , a C60 derivative, N-methyl-2-(49-pyridyl)-3,4-fulleropyrrolidine (C60PPy) was adopted to carry out the formation of the supr...

Efficiency and stability of spectral sensitization of boron-doped-diamond electrodes through covalent anchoring of a donor–acceptor organic chromophore (P1)

“…Our found maximum IPCE (Fig. [2][3][4]18,19 3.3. 4-times larger than that reported previously for a non-covalently anchored P1 to BDD.…”

Molecular Catalyst Immobilized Photocathodes for Water/Proton and Carbon Dioxide Reduction

“…p-Type dye-sensitized solar cells (p-DSCs) [18][19][20][21][22][23][24][25][26] provide an ideal model to constructadye-sensitized p-type semiconductor photocathode with catalysts for water/proton or CO 2 reduction. [27][28][29][30][31][32][33][34] In ap -DSC,the photosensitizer is attached to the surface of the semiconductor,s uch as NiO, [18] Cu 2 O, [35] CuCrO 2 , [36] and CuGaO 2 .…”

Solid state p-type dye sensitized NiO–dye–TiO2 core–shell solar cells

“…Notably, the charge transport times of both types of solar cells are almost independent of the photocurrent (light intensity), which is unusual for the conventional n-type and p-type DSCs. 26,27 One possible explanation is that the TiO 2 phase is not continuous inside the mesoporous NiO film (1.3 mm), resulting in that only a very thin NiO film coated by ALD TiO 2 works for the charge collection. Another explanation would be that holes and/or electrons transferred via the semiconductor surfaces.…”

“…28 The former one can also be applied to explain why the photocurrent is much lower than the conventional p-DSCs, although the dye regeneration in the core-shell solar cell is much faster 19 and the charge lifetime is comparable to those p-DSCs. 26,29 Therefore, making continuous TiO 2 layer or increasing the porefilling of TiO 2 inside mesoporous NiO could be a reasonable strategy to significantly improve the efficiency of such solar cells.…”