Donor–acceptor copolymers incorporating polybenzo[1,2-b:4,5-b′]dithiophene and tetrazine for high open circuit voltage polymer solar cells

Two new low band gap conjugated polymers containing a benzo[1,2-b:4,5-b′]dithiophene donor unit and a tetrazine acceptor unit were synthesized by Stille cross-coupling polymerization. The structural and thermal properties of copolymers were characterized using nuclear magnetic resonance, gel permeation chromatography and thermogravimetric analysis. The results show that the donor–acceptor copolymers thus developed have good thermal stability with decomposition temperature of 294 °C and 305 °C. Cyclic voltammetric study revealed that the copolymers possess a deep-lying highest occupied molecular orbital energy level, which is desired for high open circuit voltage polymer solar cells (PSCs) and is also favorable for stable device operation in air. Bulk-heterojunction PSCs based on blend of low band gap copolymers: [6,6]-phenyl-C71-butyric acid methyl ester on indium tin oxide/glass substrates were fabricated. This work yielded a promising power conversion efficiency of >5.0%, with a high open circuit voltage of ～1.0 V, measured under air mass 1.5 global irradiation of 100 mW/cm².     

Synthesis,optical and electrochemical properties new donor–acceptor (D–A) copolymers based on benzo[1,2-b:3,4-b′:6,5-b″] trithiophene donor and different acceptor units: Application as donor for photovoltaic devices

Two new conjugated D–A polymers P3 (PBTT-d-BTT) and P4 (PBTT-d-TPD) based on same benzo[1,2-b:3,4-b′:6,5-b″] trithiophene (BTT) donor and different acceptors monomers 5,8-dibromo-2-dodecanoylbenzo[1,2-b:3,4-b′:6,5-b″] trithiophene (d-BTT), and 1,3-dibromo-5-(2-ethylhexyl)thieno[3,4]pyrrol-4,6-dione (d-TPD) respectively, were synthesized by Stille cross-coupling reaction and characterized by gel permeation chromatography (GPC), ¹H NMR, UV–Vis absorption, thermal analysis and electrochemical cyclic voltammetry (CV) tests. Photovoltaic properties of the polymers were studied by using the polymers as donor and PC₇₁BM as acceptor with a weight ratio of polymer:PC₇₁BM 1:1, 1:2 and 1:2.5. The optimized photovoltaic device was fabricated with an active layer of a blend P3:PC₇₁BM and P4:PC₇₁BM with a blend ratio of 1:2 showed PCE 3.16% and 2.42%, respectively under illumination of AM 1.5 at 100 mW/cm² with solar simulator. The PCE of the device based on P3:PC₇₁BM processed with DIO/o-DCB has been further improved up to 4.64% with J_sc of 10.52 mA/cm² and FF of 0.58 attributed to the increase in crystalline nature of active layer and more balanced charge transport in the device, induced by DIO additive.     

14-b 400-ksps 2.5-mW连续时间∑-Δ调制器

连续时间∑-△调制器较之传统的开关电容∑-△调制器具有更低的功耗、更小的面积,以及集成抗混叠滤波器等诸多优势.设计了一种应用于低中频GSM接收机的4阶单环单比特结构的连续时间∑-△调制器.在调制器中,采用了开关电容D/A转换器,以降低时钟抖动对性能的影响.仿真结果显示,在1.8 V工作电压、200 kHz信号带宽、0.18 μm CMOS工艺条件下,采样频率21 MHz,动态范围(DR)超过90 dB,功耗不超过2.5 mW.     

14-b400-ksps 2.5-mW连续时间Σ-Δ调制器

连续时间Σ-Δ调制器较之传统的开关电容Σ-Δ调制器具有更低的功耗、更小的面积,以及集成抗混叠滤波器等诸多优势。设计了一种应用于低中频GSM接收机的4阶单环单比特结构的连续时间Σ-Δ调制器。在调制器中,采用了开关电容D/A转换器,以降低时钟抖动对性能的影响。仿真结果显示,在1.8 V工作电压2、00 kHz信号带宽、0.18μm CMOS工艺条件下,采样频率21 MHz,动态范围(DR)超过90 dB,功耗不超过2.5 mW。     

Efficient solution processed D1-A-D2-A-D1 small molecules bulk heterojunction solar cells based on alkoxy triphenylamine and benzo[1,2-b:4,5-b′]thiophene units

Two molecules denoted as VC96 and VC97 have been synthesized for efficient (η = 6.13% @ 100 mW/cm² sun-simulated light) small molecule solution processed organic solar cells. These molecules have been designed with the D₁-A-D₂-A-D₁ structure bearing different central donor unit, same benzothiadiazole (BT) as π-acceptor and end capping triphenylamine. Moreover, the optical and electrochemical properties (both experimental and theoretical) of these molecules have been systematically investigated. The solar cells prepared from VC96:PC₇₁BM and VC97:PC₇₁BM (1:2) processed from CF (chloroform) exhibit a PCE (power conversion efficiency) of η = 4.06% (J_sc = 8.36 mA/cm², V_oc = 0.90 V and FF = 0.54) and η = 3.12% (J_sc = 6.78 mA/cm², V_oc = 0.92 V and FF = 0.50), respectively. The higher PCE of the device with VC96 as compared to VC97 is demonstrated to be due to the higher hole mobility and broader IPCE spectra. The devices based on VC96:PC₇₁BM and VC97:PC₇₁BM processed with solvent additive (3 v% DIO, 1,8-diiodooctane) showed PCE of η = 5.44% and η = 4.72%, respectively. The PCE device of optimized VC96:PC₇₁BM processed with DIO/CF (thermal annealed) has been improved up to 6.13% (J_sc = 10.72 mA/cm², V_oc = 0.88 V and FF = 0.61). The device optimization results from the improvement of the balanced charge transport and better nanoscale morphology induced by the solvent additive plus the thermal annealing.     

A 1.5 V 10-b 30-MS/s CMOS pipelined analog-to-digital converter

A 1.5 V 10-b 30MS/s CMOS pipelined analog-to-digital converter (ADC) is described. Low-voltage techniques are proposed for pipelined analog-to-digital converter that avoids the use of low-threshold voltage process, on-chip clock voltage doubler, bootstrapped switch, or switched-opamp technique. At the front-end, a low-voltage S/H circuit with cross-coupled input sampling switch is employed to eliminate the input signal feedthrough and enhance the dynamic performance of the pipelined ADC. Multiplying digital-to-analog converter (MDAC) with cross-coupled configuration also provides an effective common-mode feedback to overcome the problem of common-mode accumulation. The prototype chips have been fabricated and experimental results confirm the feasibility of this new technique.     

一种12-b 125 kSPS全差分CMOS SAR A/D转换器

设计了一种基于1stSilicon0.25μmCMOS工艺的全集成SARA/D转换器。详细介绍了SARA/D转换器的基本原理、电路结构和仿真结果。该SARA/D转换器采用全差分结构,系统时钟频率为2MHz,精度12位,采样速率125kb/s,输入电压范围0～2.5V。在3.3V供电电压下,功耗为0.3mW,芯片有效面积为745μm×2000μm。     

A 30-mW 8-b 125-MS/s pipelined ADC in 0.13-μm CMOS

An 8-b pipelined ADC constructed in 0.13-μm CMOS is described. This ADC uses a dual-supply technique to yield 8-b performance at a sampling rate of 125 MS/s while consuming 30 mW from 1.8-V and 1.2-V supplies. Active area is 0.4 mm². Numerous challenges associated with this choice of process technology were overcome, such as limited dynamic range, copper metallization and the effects of gate oxide leakage.     

Solution-processable star-shaped photovoltaic organic molecule with triphenylamine core and thieno[3,2-b]thiophene–dicyanovinyl arms

A new solution-processable star-shaped D-π-A molecule with triphenylamine (TPA) as core and donor unit, dicyanovinyl (DCN) as end group and acceptor unit, and 3,6-dihexyl-thieno[3,2-b]thiophene (DHT) as π bridge, S(TPA-DHT-DCN) was synthesized for the application as donor material in solution-processed bulk-heterojunction organic solar cells (OSCs). The compound exhibits broad absorption in the visible region with suitable energy levels, which are desirable for application as a donor material in organic solar cells. The OSC devices based on S(TPA-DHT-DCN) as the donor and PC₇₁BM as the acceptor (1:2, w/w) exhibited power conversion efficiency (PCE) of 2.87%, with high open circuit voltage (V_oc) of 0.96 V, short circuit current density (J_sc) of 6.80 mA/cm², and fill factor (FF) of 43.5%, under the illumination of AM.1.5, 100 mW/cm². The V_oc of 0.96 V for S(TPA-DHT-DCN) is among the top values for the solution-processed molecular-based OSCs reported so far.     

A 10-b 120-MS/s 45?nm CMOS ADC using a re-configurable three-stage switched amplifier

A 10-b 120-MS/s pipeline analog-to-digital converter (ADC) is implemented in a 45?nm CMOS process. Three-stage amplifiers based on reversed nested Miller compensation and Multipath zero cancellation techniques are employed in the input sample-and-hold amplifier (SHA) and two multiplying digital-to-analog converters (MDACs). A single re-configurable three-stage switched amplifier is shared between two adjacent MDACs without MOS series switches and memory effects by employing two separate NMOS input pairs. A charge redistributed input sampling network properly handles both single-ended and differential SHA inputs with a swing range of 1.2?Vpp around a 1.6?V common-mode voltage. The prototype ADC with an active die area of 0.58?mm² consumes 61.6?mW at 120?MS/s and 1.1?V. The measured differential and integral nonlinearities are within ±0.44 and ±0.75?LSB, respectively. At a sampling rate of 120?MHz with a 4.2?MHz sinusoidal input, the measured maximum signal-to-noise-and-distortion ratio and spurious-free dynamic range are 55.6 and 70.4?dB, respectively.     

A 1.0-V 6-b 40 MS/s time-domain flash ADC in 0.18 μm CMOS

This paper presents a 6-bit low power low supply voltage time-domain comparator. The conventional voltage comparison is moved to time-domain so as to remove pre-amplifier and latch, which enables its feasibility to low supply voltage. The voltage-to-time converter is realized by the proposed linear pulse-width-modulation. The set-up time of the D flip-flop determines the sampling rate of the converter. The resistive averaging relaxes the matching requirement of the parallel comparison cells. The total input capacitance is decreased to less than 40fF in this architecture. The above digital-intensive setting makes the analog-to-digital converter (ADC) benefit from technology scaling in both power consumption and sampling rate. The prototype ADC is fabricated in SMIC 0.18 μm CMOS process. At 40 MS/s and 1.0-V supply, it consumes 540 μW and achieves an effective-number-of-bit of 5.43, resulting in a figure-of-merit of 0.31 pJ/conversion-step and active area of 0.1 mm².     

一种8-b 180KSPS的带有新颖的时域比较器且有效位数7.97的差分逐次逼近模数转换器

This paper presents a differential successive approximation register analog-to-digital converter (SAR ADC) with a novel time-domain comparator design for wireless sensor networks. The prototype chip has been implemented in the UMC 0.18-μ m 1P6M CMOS process. The proposed ADC achieves a peak ENOB of 7.98 at an input frequency of 39.7 kHz and sampling rate of 180 kHz. With the Nyquist input frequency, 68.49-dB SFDR, 7.97-ENOB is achieved. A simple quadrate layout is adopted to ease the routing complexity of the common-centroid symmetry layout. The ADC maintains a maximum differential nonlinearity of less than 0.08 LSB and integral nonlinearity less than 0.34 LSB by this type of layout.     

2,7-二癸基-[1]苯并噻吩[3,2-b][1]-苯并噻吩的制备及性能研究

以邻氯苯甲醛、NaHS·xH2O、癸酰氯为原料,经消去、酰化,还原反应合成2,7-二癸基二苯并二噻吩(C10-BTBT)。通过核磁共振表征和确证。本文研究了C10-BTBT光学性能、热学性能、电学性能以及环境稳定性。紫外-荧光光谱研究证明,化合物在近紫外光激发下发出明亮的蓝光,发射中心波长在352nm。液晶相的相转变温度通过差热扫描仪测定,测量结果为熔点Tcp=112℃,清亮点Tmp=125℃。通过喷墨打印技术制备了底栅顶接触结构的2,7-二癸基二苯并二噻吩的OTFT器件,场效应平均迁移率达到0.1cm2/V·s,最大迁移率达到0.25cm2/V·s,开关比超过104。放置空气中不同时间,器件开态电流和开关比没有较大变化。     

Triisopropylsilyl-Substituted Benzo[1,2-b:4,5-c′]dithiophene-4,8-dione-Containing Copolymers with More Than 17% Efficiency in Organic Solar Cells

Considering the special functions of fused-ring aromatic building blocks and Si-atom in high-performance donor–acceptor-conjugated materials at the same time, herein the synthesis of a novel fused-ring tricyclic heterocycle, triisopropylsilyl-substituted benzo[1,2-b:4,5-c′]dithiophene-4,8-dione (iBDD-Si), an isomer of well-known benzo[1,2-c:4,5-c′]dithiophene-4,8-dione is presented. The iBDD-Si-based copolymer series (PM6, PM6-5Si, PM6-10Si, and PM6-15Si) is synthesized via Stille polymerization, revealing fine-tuned optical and electrochemical properties, and molecular packing with varying iBDD-Si contents in the backbone. Organic solar cells are fabricated by pairing the copolymer donors with nonfullerene acceptor N3 and characterized. High power conversion efficiency of more than 17% is achieved using the PM6-5Si-based solar cell, which is attributed to the balanced charge transport, enhanced charge generation/dissociation kinetics, and minimized total energy and recombination losses. It is demonstrated that iBDD-Si is a promising backbone toolbox for various high-performance conjugated materials.     

Novel dithieno[3,2-b:2′,3′-d]pyrrole-based organic dyes with high molar extinction coefficient for dye-sensitized solar cells

Three new metal-free organic dyes FD1–3 with a planar dithieno[3,2-b:2′,3′-d]pyrrole unit as linker were synthesized and used for dye-sensitized solar cells with high molar extinction coefficients. In this work, dithieno[3,2-b:2′,3′-d]pyrrole was employed as π-conjugated bridge to construct A–π–d–π–A organic dyes, where 9,9-dihexyl-9H-fluorene was used as a donor, and cyanoacrylic acid as an electron acceptor. For a typical device, a solar energy conversion efficiency (η) of 6.36% based on FD2 was achieved under simulated AM 1.5 solar irradiation (100 mW cm^?2) with a short-circuit photocurrent density (J_sc) of 13.76 mA cm^?2, an open-circuit voltage (V_oc) of 669 mV, a fill factor (ff) of 0.691. The results suggest that the organic dye with a functionalized dithienopyrrole unit is a promising candidate for DSSCs due to its high molar extinction coefficients.     

An 8.38?fJ/conversion-step 0.6?V 8-b 4.35?MS/s asynchronous SAR ADC in 65?nm CMOS

An asynchronous reference-free successive-approximation register analog-to-digital converter (ADC) in 65?nm CMOS is presented. In order to fit for low supply voltage design in advanced digital sub-nanometer process, a differential time-domain comparator is implemented. It tracks process variation with unit transistor of input device as well as charging capacitor, and enables differential configuration by using RS trigger instead of D-flip-flop. The proposed architecture is digital circuits heavily involved; therefore it will benefit from technology scaling. The power dissipation is further improved by means of asynchronous architecture, which is adjusted for low supply voltage operation, as well as reference-free configuration. The prototype ADC is fabricated in SMIC 65?nm digital CMOS process. It has signal to noise and distortion ratio of 46.7?dB at the sampling rate of 4.35?MS/s while consuming 6.6???W from 0.6-V power supply. It maintains linearity over 7-bit when the input frequency is lower than 5?MHz. The figure of merit of 8.38?fJ/conversion-step and die area of 0.011?mm² is achieved.     

Synthesis and photovoltaic properties of organic dyes containing N-fluoren-2-yl dithieno[3,2-b:2′,3′-d]pyrrole and different donors

New organic dyes containing fluorene appended dithienopyrrole as electron rich linker, different arylamine/heterocyclic units as conjugating donors and cyanoacrylic acid as acceptor have been synthesized and characterized as sensitizers for dye-sensitized solar cells. The effect of different conjugated donors such as triarylamine, carbazole and phenothiazine on the photophysical, electrochemical and photovoltaic properties is investigated. The optical and electrochemical properties of the dyes are strongly influenced by conjugating donors. The dye containing phenothiazine donor exhibited longer wavelength absorption and low oxidation potential. The time dependent density functional calculations performed on the dye models reveal charge transfer character for the longer wavelength absorption. The dye-sensitized solar cells fabricated using a dye containing fluorenyldiphenylamine donor displayed highest power conversion efficiency (6.81%) in the series originating from the high short circuit current density (J_SC = 14.01 mA cm⁻²) and high open circuit voltage (V_OC = 738 mV).     

Copoly[6,6′-bis(9-(2-ethylhexyl)carbazole-3-yl)/thieno-(2,5-b)thiophenylidenevinylene]-based photorefractive composite: A comparative study on conjugated and non-conjugated polymer systems

Photoconductivity and birefringence are two important factors that affect performances of photorefractive devices. Here, the optical properties of this composite based on copoly[6,6′-bis(9-(2-ethylhexyl)carbazole-3-yl)/thieno-(2,5-b)thiophenylidenevinylene] as photoconducting material, 2-[3-[(E)-2(piperidine)-1-ethenyl]-5,5-dimethyl]-2-cyclohexenyliden]malononitrile as nonlinear optical chromophore, butyl benzyl phthalate as plasticizer and C₆₀ as photosensitizer, has been compared to those of the corresponding non-π-conjugated polymer composite. The 50-μm thick photorefractive composite showed a diffraction efficiency 37.2% at 50 V/μm, which corresponded to a Δn of 2.62 × 10^?3. When we compare the speeds of the current and the non-conjugated analogue composites, the current composite has about a factor of seven larger speeds due to the π-conjugated polymer backbone. We also discuss and present simple explanation of the observed effect.