Alcohol-based
bifunctional ammonium cations, 2-hydroxyethylammonium
(HEA+), HO(CH2)2NH3
+, were introduced into formamidinium (FA+) tin-based
perovskites (HEA
x
FA1–x
SnI3; x = 0–1)
to absorb light in carbon-based mesoscopic solar cells. We found that
HEA+ cations play a key role to control the crystal structures,
the lattice structures altered from orthorhombic (x = 0) to rhombohedral (x = 0.2–0.4) with
greater symmetry. When x was increased to 0.6–1.0,
tin and iodide vacancies were formed to generate 3D-vacant perovskites
(HEA
x
FA1–x
Sn0.67I2.33, x ≥
0.6) with a tetragonal structure. Tin-based perovskites in this series
were fabricated into mesoporous solar cells using one-step drop-cast
(DC), two-step solvent-extraction (SE), and SE + 3% ethylenediammonium
diiodide (EDAI2) as an additive. After optimization of
device performance with the SE + 3% EDAI2 approach, the
HEA0.4FA0.6SnI3 (HEAI = 40%) device
gave the best photovoltaic performance with J
SC = 18.52 mA cm–2, V
OC = 371 mV, FF = 0.562, and overall efficiency η = 3.9%
after the device was stored for a period of 340 h.
Two random (Zn(II)-based P1-P2) and two alternating (Ru(II)-based P3-P4) metallo-copolymers containing bis-terpyridyl ligands with various central donor (i.e., fluorene or carbazole) and acceptor (i.e., benzothiadiazole) moieties were synthesized. The effects of electron donor-acceptor interactions with metal (Zn(II) and Ru(II)) ions on their thermal, optical, and electrochemical properties were investigated. Because of the strong ICT transitions between donor and acceptor ligands in both Zn(II)- and Ru(II)-based metallo-coplymers and MLCT transitions in Ru(II)-based metallo-coplymers, the absorption spectra covered a broad range of 260-750 nm with the band gaps of 1.57-1.77 eV. In addition, the introduction of Ru(II)-based metallo-coplymer P4 mixed with PC(60)BM as an active layer of the BHJ solar cell device exhibited the highest PCE value up to 0.90%.
Two b-cyano-thiophenevinylene-based polymers containing cyclopentadithiophene (CPDT-CN) and dithienosilole (DTS-CN) units were synthesized via Stille coupling reaction with Pd(PPh 3 ) 4 as a catalyst. The effects of the bridged atoms (C and Si) and cyano-vinylene groups on their thermal, optical, electrochemical, charge transporting, and photovoltaic properties were investigated. Both polymers possessed the highest occupied molecular orbital (HOMO) levels of about À5.30 eV and the lowest unoccupied molecular orbital (LUMO) levels of about À3.60 eV, and covered broad absorption ranges with narrow optical band gaps (ca. 1.6 eV). The bulk heterojunction polymer solar cell (PSC) devices containing an active layer of electron-donor polymers (CPDT-CN and DTS-CN) blended with an electron-acceptor, that is, [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM) or [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM), in different weight ratios were explored under 100 mW/cm 2 of AM 1.5 white-light illumination. The PSC device based on DTS-CN:PC 71 BM (1:2 w/w) exhibited a best power conversion efficiency (PCE) value of 2.25% with V oc ¼ 0.74 V, J sc ¼ 8.39 mA/cm 2 , and FF ¼ 0.36. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 3417-3425, 2011
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