A Non-Conjugated Polymer Acceptor for Efficient and Thermally Stable All-Polymer Solar Cells

A non-conjugated polymer acceptor PF1-TS4 was firstly synthesized by embedding a thioalkyl segment in the mainchain, which shows excellent photophysical properties on par with a fully conjugated polymer, with a low optical band gap of 1.58 eV and a high absorption coefficient >10⁵ cm⁻¹, a high LUMO level of −3.89 eV, and suitable crystallinity. Matched with the polymer donor PM6, the PF1-TS4-based all-PSC achieved a power conversion efficiency (PCE) of 8.63 %, which is ≈45 % higher than that of a device based on the small molecule acceptor counterpart IDIC16. Moreover, the PF1-TS4-based all-PSC has good thermal stability with ≈70 % of its initial PCE retained after being stored at 85 °C for 180 h, while the IDIC16-based device only retained ≈50 % of its initial PCE when stored at 85 °C for only 18 h. Our work provides a new strategy to develop efficient polymer acceptor materials by linkage of conjugated units with non-conjugated thioalkyl segments.     

Hot Branching Dynamics in a Light‐Harvesting Iron Carbene Complex Revealed by Ultrafast X‐ray Emission Spectroscopy

Iron N‐heterocyclic carbene (NHC) complexes have received a great deal of attention recently because of their growing potential as light sensitizers or photocatalysts. We present a sub‐ps X‐ray spectroscopy study of an Fe^IINHC complex that identifies and quantifies the states involved in the deactivation cascade after light absorption. Excited molecules relax back to the ground state along two pathways: After population of a hot ³MLCT state, from the initially excited ¹MLCT state, 30 % of the molecules undergo ultrafast (150 fs) relaxation to the ³MC state, in competition with vibrational relaxation and cooling to the relaxed ³MLCT state. The relaxed ³MLCT state then decays much more slowly (7.6 ps) to the ³MC state. The ³MC state is rapidly (2.2 ps) deactivated to the ground state. The ⁵MC state is not involved in the deactivation pathway. The ultrafast partial deactivation of the ³MLCT state constitutes a loss channel from the point of view of photochemical efficiency and highlights the necessity to screen transition‐metal complexes for similar ultrafast decays to optimize photochemical performance.     

A high statistics measurement of the Lambda(+)(c) lifetime

A high statistics measurement of the Lambda(+)(c) lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat) +/- 2.5 (syst) fs from 8034 +/- 122 Lambda(+)(c)-->pK(-)pi(+) decays represents a significant improvement over the present world average.     

Quantum oscillatory phenomena in graphite intercalated with AsF5

Both Shubnikov-de Haas and de Haas-van Alphen oscillations are reported for C_8nAsF₅ (n=1,2, is the stage number). The observed oscillations are interpreted in terms of a tight-binding model for the band structure, and good agreement with both band parameters and effective carrier masses is found. In addition, the effective charge transfer per AsF₅ molecule (f=.37 for stage 1, =.41 for stage 2) is in basic agreement with previous determinations.     

Experimental evidence for a light and broad scalar resonance in D(+) --> pi(-)pi(+)pi(+) decay

From a sample of 1172 +/- 61 D(+)-->pi(-)pi(+)pi(+) decays, we find gamma(D(+)-->pi(-)pi(+)pi(+))/gamma(D(+)-->K-pi(+)pi(+)) = 0.0311 +/- 0.0018(+0.0016)(-0.0026). Using a coherent amplitude analysis to fit the Dalitz plot of these decays, we find strong evidence that a scalar resonance of mass 478(+24)(-23) +/- 17 MeV/c(2) and width 324(+42)(-40) +/- 21 MeV/c(2) accounts for approximately half of all decays.     

Green polymer chemistry: Telechelic poly(ethylene glycol)s via enzymatic catalysis

This article reports our discovery that poly(ethylene glycol) (PEG) can quantitatively be functionalized by transesterification using Candida antarctica lipase B (Novozyme 435) as the catalyst. α‐ω telechelic PEG‐methacrylates and PEG‐acetates were successfully prepared using commercially available PEGs with both narrow and broad molecular weight distribution. ¹H and ¹³C NMR together with MALDI‐TOF mass spectroscopy verified the expected structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3024–3028, 2008     

Untersuchung von Wasser

Ohne Zusammenfassung