Yuan Xie

Series-resonant vibrating micromechanical resonator oscillators are demonstrated using a custom-designed single-stage zero-phase-shift sustaining amplifier together with planar-processed micromechanical resonator variants with quality factors Q in the thousands that differ mainly in their power-handling capacities. The resonator variants include two 40-/spl mu/m-long 10-MHz clamped-clamped-beam (CC-beam) resonators, one of them much wider than the other so as to allow larger power-handling capacity, and a 64-/spl mu/m-diameter 60-MHz disk resonator that maximizes both Q and power handling among the resonators tested. Tradeoffs between Q and power handling are seen to be most important in setting the close-to-carrier and far-from-carrier phase noise behavior of each oscillator, although such parameters as resonant frequency and motional resistance are also important. With a 10/spl times/ higher power handling capability than the wide-width CC-beam resonator, a comparable series motional resistance, and a 45/spl times/ higher Q of 48 000, the 60-MHz wine glass resonator reference oscillator exhibits a measured phase noise of -110 dBc/Hz at 1-kHz offset, and -132 dBc/Hz at far-from-carrier offsets. Dividing down to 10 MHz for fair comparison with a common conventional standard, this oscillator achieves a phase noise of -125 dBc/Hz at 1-kHz offset, and -147 dBc/Hz at far-from-carrier offsets.

A vibrating polysilicon micromechanical "hollow-disk" ring resonator obtained by removing quadrants of material from a solid disk resonator, but purposely leaving intact beams of material to non-intrusively support the structure, has been demonstrated in several vibration modes spanning frequencies from HF (24.4 MHz), to VHF (72.1MHz), to UHF (1.169 GHz), with Q's as high as 67,519, 48,048, and 5,846, respectively. Furthermore, the use of notched support attachments closer to actual extensional ring nodal points raises the Q to 14,603 at 1.2 GHz, which is the highest yet achieved past 1 GHz, and which clearly illustrates the utility of notching for substantially higher Q. At 1.2 GHz, a combination of high Q and larger capacitive transducers allows the notched version to achieve an R/sub x/ of only 282 k/spl Omega/, which is 12X smaller than achieved by previous pure polysilicon surface-micromachined solid disk resonators in the GHz range.

A new acceptor–donor–acceptor-structured nonfullerene acceptor, 2,2′-((2Z,2′Z)-(((4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-4,3-diyl))bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (i-IEICO-4F), is designed and synthesized via main-chain substituting position modification of 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)dimalononitrile. Unlike its planar analogue IEICO-4F with strong absorption in the near-infrared region, i-IEICO-4F exhibits a twisted main-chain configuration, resulting in 164 nm blue shifts and leading to complementary absorption with the wide-bandgap polymer (J52). A high solution molar extinction coefficient of 2.41 × 105 M–1 cm–1, and sufficiently high energy of charge-transfer excitons of 1.15 eV in a J52:i-IEICO-4F blend were observed, in comparison with those of 2.26 × 105 M–1 cm–1 and 1.08 eV for IEICO-4F. A power conversion efficiency of 13.18% with an open-circuit voltage (0.849 V), a short-circuit current density of 22.86 mA cm–2, and a fill factor of 67.9% were recorded in J52:i-IEICO-4F-based polymer solar cells (PSCs), demonstrating that this main-chain twisted strategy can be a guideline that facilitates the development of new acceptors to maximize the efficiency in PSCs.