Solution Processable Deep-Blue OLEDs Based on Benzimidazole-TPA Conjugated through 9,9-Diethyl Fluorene (D-π-A) Luminophore with a Hybridized Local and Charge Transfer Excited State

Blue emitters with outstanding luminous performance must be synthesized for full-color organic light-emitting diode displays. The hybridized local and charge transfer (HLCT) is a remarkable excited state that combines the local and CT state to ensure a significant fluorescence quantum yield. The ambition of this study is to implement a subtle interpretation of photophysical and electroluminescence (EL) properties. To understand more about the geometry and orientations, the density functional theories were studied. Herein, we present a hybrid donor-π-acceptor blue-emitting fluorophore with a twisted geometry, in which triphenylamine (TPA) acts as a donor, 9,9 diethylfluorene acts as a spacer, and benzilimidazole acts as an acceptor. The EL spectra of the device are very similar to spectra of photoluminescence in the solution phase. Among all, the best performing 15 wt % MCFBI-fl-TPA-based OLED device illustrates a maximum luminance of 3290 cd/m2. The device shows 8.2 lm W-1 of power efficiency, 7.9 cd A-1 of current efficiency, and 3.5% of high external quantum efficiency with (0.20, 0.23) of CIE coordinates of the device emitting blue color

Multifunctional 4,5-Diphenyl-1H-imidazole-Based Luminogens as Near UV/Deep Blue Emitters/Hosts for Organic Light-Emitting Diodes and Selective Picric Acid Detection

A series of luminophores (construction of diphenylimidazole (m-CF3PTPI) groups functionalized at the N1-positions of imidazole groups) were purposefully designed and synthesized for optoelectronics and for selective detection of nitroaromatic compounds. The luminophores showed deep blue emission in solution, solid, and thin-film matrix with acceptable quantum yield and good thermal stability (5% weight loss at 258–296 °C). From electrochemical analysis as well as theoretical calculations, the energy gaps of HOMO–LUMO are found to be in good agreement and all of them showed good triplet energy. The luminophores can be explored as hosts for phosphorescent organic light-emitting diodes (PhOLEDs). Furthermore, the m-CF3PTPI derivatives were used as emitters for fluorescent OLEDs and hosts (m-CF3PTPI-1 and m-CF3PTPI-2) for triplet dopants in PhOLEDs. Near-UV emissions were observed for all the doped devices that exhibited electroluminescence (EL) peaks at ∼380–395 nm with a Commission International deL’Eclairage (CIEy) coordinate of ∼0.09. Of all the devices, the m-CF3PTPI-5 (3 wt %)-based device demonstrated a maximum external quantum efficiency (EQEmax) of 2.8%, power efficiency (PEmax) of 0.9 lm/W, current efficiency (CEmax) of 1.3 cd/A, and brightness of 953 cd/m2. Moreover, the device was further optimized using a different host approach. SimCP2 displayed the best performance by achieving a high EQEmax of 4.0% that is near the theoretical limit of fluorescent materials

A Microscopic Analysis of TCP Performance over Wireless Ad-hoc Networks

this paper is to study the performance of the TCP transport layer protocol over ad-hoc networks. Recent works in transport protocols for ad-hoc networks have investigated the impact of ad-hoc network characteristics on TCP's performance, and proposed schemes that help TCP overcome the negative impact of such characteristics as random wireless loss and mobility. The primary mechanism proposed involves sending an explicit link failure notification (ELFN) to the source from the point of link failure. The source, upon receiving the ELFN freezes TCP's timers and state, re-computes a new route to the destination, and either releases the timers and state or re-starts them from their respective initial values. While the goal of ELFN based approaches is to prevent the route disruption time from adversely impacting TCP's performance, in this paper we contend that there are several other factors that influence TCP's performance degradation. We briefly outline the different factors below

TCP performance over mobile ad-hoc networks: A quantitative study

In this paper we study the performance of TCP over mobile ad-hoc networks. We present a compre-hensive set of simulation results and identify the key factors that impact TCP’s performance over ad-hoc networks. We use a variety of parameters including link failure detection latency, route computation la-tency, packet level route unavailability index, and flow level route unavailability index to capture the impact of mobility. We relate the impact of mobility on the different parameters to TCP’s performance by studying the throughput, loss-rate, and retransmission timeout values at the TCP layer. We conclude from our results that existing approaches to improve TCP performance over mobile ad-hoc networks have identified and hence focused only on a subset of the affecting factors. In the process we identify a comprehensive set of factors influencing TCP performance. Finally, using the insights gained through the performance evalua-tions, we propose a framework called Atra consisting of three simple and easily implementable mechanisms at the MAC and routing layers to improve TCP’s performance over ad-hoc networks. We demonstrate that Atra improves on the throughput performance of a default protocol stack by 50-100%. I

ATP: A Reliable Transport Protocol for Ad-hoc Networks

Existing works have approached the problem of reliable transport in ad-hoc networks by proposing mechanisms to improve TCP’s performance over such networks. In this paper we show through detailed arguments and simulations that several of the design elements in TCP are fundamentally inappropriate for the unique characteristics of ad-hoc networks. Given that ad-hoc networks are typically stand-alone, we approach the problem of reliable transport from the perspective that it is justifiable to develop an entirely new transport protocol that is not a variant of TCP. Toward this end, we present a new reliable transport layer protocol for ad-hoc networks called ATP (ad-hoc transport protocol). We show through ns2 based simulations that ATP outperforms default TCP as well as TCP-ELFN and ATCP