High-efficiency inverted polymer solar cells via dual effects of introducing the high boiling point solvent and the high conductive PEDOT:PSS layer

Polymer solar cells (PSCs) are of great interest in the past decade owing to their potentially low-cost in the manufacturing by the solution-based roll to roll method. In this paper, a novel inverted device structure was introduced by inserting a high conductive PEDOT:PSS (hcPEDOT:PSS) layer between the Au nanoparticles (NPs)-embedded hole transport layer (PEDOT:PSS) and the top electrode layer. Power conversion efficiency (PCE) initially reached up to 4.51%, illustrating ∼10% higher compared with the device similarly enhanced by Au NPs plasmonics where only one PEDOT:PSS layer with the embedded Au NPs was used in single bulk heterojunction inverted PSCs based on the poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methylester (P3HT:PCBM). The PCE was further improved from 4.51% to 5.01% by adding the high-boiling point solvent of 1,8-diiodooctane (DD) into the active layer, presenting ∼20% enhancement in PCE through dual effects of introducing the high boiling point solvent and the high conductive PEDOT:PSS layer. Morphologies of the active layers were characterised by SEM and AFM separately in the paper.     

Efficient recyclable organic solar cells on cellulose nanocrystal substrates with a conducting polymer top electrode deposited by film-transfer lamination

We report on efficient solar cells on recyclable cellulose nanocrystal (CNC) substrates with a new device structure wherein polyethylenimine-modified Ag is used as the bottom electron-collecting electrode and high-conductivity poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS, PH1000) is used as the semitransparent top hole-collecting electrode. The PEDOT:PSS top electrode is deposited by a film-transfer lamination technique. This dry process avoids swelling damage to the CNC substrate, which is observed when PEDOT:PSS is directly spin-coated from an aqueous solution. Solar cells on recyclable CNC substrates exhibit a maximum power conversion efficiency of 4.0% with a large fill factor of 0.64 ± 0.02 when illuminated through the top semitransparent PEDOT:PSS electrode. The performance of solar cells on CNC substrates is comparable to that of reference solar cells on polyethersulfone substrates.     

1064-nm DFB laser diode modules applicable to seeder for pulse-on-demand fiber laser systems

Semiconductor DFB (Distributed feedback) laser diodes with an operating wavelength of 1064 nm, which is suitable for pulse-on-demand fiber laser, have been developed. The stable performance of CW and nanosecond/picosecond pulsed operation is reviewed. By applying gain-switching operation with a simple direct modulation technique, 50-ps pulse generation with a stable spectral single-mode property was obtained. For the efficient amplification of the obtained 50-ps pulse, a monolithic semiconductor optical amplifier (SOA) was integrated into the DFB lasers. An improved peak power of 300 mW at 50-ps pulse was observed with limited optical noise injection when the synchronous modulation technique of the DFB and the SOA was employed. Short cavity lasers showed a high-frequency response compared to the original DFB lasers and achieved a short pulse width of 13 ps by standard gain-switched operation.     

一种无线宽带收发机I/Q失配校准和补偿技术

本文提出一种基于数字基带的无线宽带收发机中的发射链路I/Q失配的校准和补偿技术。数字基带发射用于I/Q失配校准的信号,经过RF收发机的发射链路、由平方功率检测器、带通滤波器组成的校准通路以及RF接收机的可变增益放大器,数字基带采集此信号并估计I/Q失配的大小,完成I/Q失配的校准和补偿,此技术相比于射频的自校准节省了面积和功耗。本技术已经成功用于IEEE802.11n,可以实现50dB以上的镜像抑制,完全满足了系统要求。     

Fabrication of organic flexible electrodes using transfer stamping process

A transfer stamping process is proposed to fabricate micro-scale organic flexible electrodes. With different adhesion forces of the transferring interfaces, ink/mold and ink/substrate, patterns are formed from the relief features of the elastomeric mold to the substrate without residual layer, and no complex pre-process and steps are needed. To estimate the deformation during pressing, the sagging height of the mold is analyzed with finite element method (FEM). Two conductive polymers, PEDOT:PSS and silver paste, are transferred from the flat relief features of the mold to the PET substrate. The coating characteristics and problems are discussed. The transfer stamping process is also employed to fabricate electrodes on the dielectric/ITO film and to form an organic flexible capacitance. This paper demonstrates the potential of transfer stamping in fabricating organic electronic components, such as organic integrated circuit, OLED and OTFT.     

MOCVD生长的GaN 薄膜中缺陷团引起的X射线漫散射研究

采用高分辨X射线衍射对在蓝宝石(0001)面生长的GaN外延膜的漫散射进行了研究.结果表明,GaN薄膜中存在缺陷团,其浓度随着穿透位错密度的增加而增加,其平均半径呈相反趋势.基于位错是点缺陷的聚集区,缺陷团优先在位错附近形成的效应对结果进行了解释.同时发现电子迁移率随缺陷团浓度的增加而减少.     

Matrix Manipulation of Directly-Synthesized PbS Quantum Dot Inks Enabled by Coordination Engineering

The direct-synthesis of conductive PbS quantum dot (QD) ink is facile, scalable, and low-cost, boosting the future commercialization of optoelectronics based on colloidal QDs. However, manipulating the QD matrix structures still is a challenge, which limits the corresponding QD solar cell performance. Here, for the first time a coordination-engineering strategy to finely adjust the matrix thickness around the QDs is presented, in which halogen salts are introduced into the reaction to convert the excessive insulating lead iodide into soluble iodoplumbate species. As a result, the obtained QD film exhibits shrunk insulating shells, leading to higher charge carrier transport and superior surface passivation compared to the control devices. A significantly improved power-conversion efficiency from 10.52% to 12.12% can be achieved after the matrix engineering. Therefore, the work shows high significance in promoting the practical application of directly synthesized PbS QD inks in large-area low-cost optoelectronic devices.     

High efficient OLEDs based on novel Re(I) complexes with phenanthroimidazole derivatives

Novel rhenium(I) [Re(I)] complexes with phenanthroimidazole ligands were successfully designed, synthesized and characterized. The Re(I) complexes displayed intense phosphorescence with yellow or orange color around 540–580 nm at room temperature with relatively short lifetimes. The phosphorescent simple-structure OLEDs using these Re(I) complexes as dopants exhibited low turn-on voltage of 3.5–3.6 V, maximum current efficiencies of 18.7–21.1 cd A⁻¹ and maximum power efficiencies of 13.3–18.9 lm W⁻¹, which were amongst the highest reported for OLEDs based on Re(I) complexes with phenanthroline ligands as emitters. The excellent performances are due to the bulky steric Re(I) complexes with short lifetime and good electron-transporting ability, which may improve the electron injection and result in greater balance between electron and hole fluxes. The results suggest that these complexes have potential application in OLEDs.     

Anti-vapor-penetration and condensate microdrop self-transport of superhydrophobic oblique nanowire surface under high subcooling

It is well-known that microscale gaps or defects are ubiquitous and can be penetrated by vapor,resulting in the failure of superhydrophobic effect and undesired condensate flooding under high subcooling.Here,we propose and demonstrate that such problem can be solved by the oblique arrangement of nanowires.Such a structure has been demonstrated to own anti-vapor-penetration and microdrop self-transport functions under high subcooling,unaffected by the microscale gaps.This is because vapor molecules can be intercepted by oblique nanowires and preferentially nucleate at near-surface locations,avoiding the penetration of vapor into the microscale gaps.As-formed microdrops can suspend upon the nanowires and have low solid-liquid adhesion.Besides,oblique nanowires can generate asymmetric surface tension and microdrop coalescence can release driving energy,both of which facilitate the microdrop self-removal via sweeping and jumping ways.This new design idea helps develop more advanced condensation mass and heat transfer interfaces.