Distance‐Dependent Electron Transfer Kinetics in Axially Connected Silicon Phthalocyanine‐Fullerene Conjugates

Abstract

The effect of donor-acceptor distance in controlling the rate of electron transfer in axially linked silicon phthalocyanine-C 60 dyads has been investigated. For this, two C 60-SiPc-C 60 dyads, 1 and 2, varying in their donor-acceptor distance, have been newly synthesized and characterized. In the case of C 60-SiPc-C 60 1 where the SiPc and C 60 are separated by a phenyl spacer, faster electron transfer was observed with k cs equal to 2.7 × 10 9 s À 1 in benzonitrile. However, in the case of C 60-SiPc-C 60 2, where SiPc and C 60 are separated by a biphenyl spacer, a slower electron transfer rate constant, k cs = 9.1 × 10 8 s À 1 , was recorded. The addition of an extra phenyl spacer in 2 increased the donor-acceptor distance by~4.3 Å, and consequently, slowed down the electron transfer rate constant by a factor of~3.7. The charge separated state lasted over 3 ns, monitoring time window of our femtosecond transient spectrometer. Complimentary nanosecond transient absorption studies revealed formation of 3 SiPc* as the end product and suggested the final lifetime of the charge separated state to be in the 3-20 ns range. Energy level diagrams established to comprehend these mechanistic details indicated that the comparatively highenergy SiPc * +-C 60 * À charge separated states (1.57 eV) populated the low-lying 3 SiPc* (1.26 eV) prior returning to the ground state.

Tunable J-type aggregation of silicon phthalocyanines in a surface-anchored metal–organic framework thin film

“…On the other hand, SiPc 3 and SiPc 4 were obtained employing the already described mild oxidation protocol (Scheme 3), over both formyl groups of (ArO) 8 SiPc(ArCHO) 2 6 and (ArO) 8 SiPc(Ar 2 CHO) 2 7, respectively. 41 All the new compounds were unambiguously characterized by 1 H NMR and UV-vis absorption spectroscopy, and HR MALDI-TOF mass spectrometry (see Experimental section and Fig. S1-S9, ESI †).…”

Variance-resistant PTB7 and axially-substituted silicon phthalocyanines as active materials for high-Voc organic photovoltaics

“…Moreover, AFM images (Fig. 2 ) show that domain sizes are in the hundreds of nm range, which is often too large for optimal BHJ OPV operation, given the average distance travelled by excitons before recombination is around 5–15 nm 1 , 54 , 55 .…”

Interplay between Electronic Energy Transfer and Reversible Photoreactions in a Triad Comprising Two Different Styrylbenzoquinoline Photochromes and a ′Hidden′ Quencher

“…Multi-chromophoric molecular systems, including covalently linked dyads and triads, attract much attention as models for experimental and theoretical studies of inter-chromophore interactions leading to excimer formation, [1][2][3][4][5][6] energy and/or electron transfer. [7][8][9][10][11][12][13][14][15][16][17][18] In the case when chromophores are also photochromes capable of reversibly photoisomerizing between two stable forms (isomers), multi-photochromic systems can serve as molecular digital switches and logic gates. [19][20][21][22][23][24][25] However, multi-photochromic systems, as compared with single photochromes, often undergo other (side) reactions, which limits possible applications of the former.…”