Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is most commonly used as an anode buffer layer in bulk-heterojunction (BHJ) polymer solar cells (PSCs). However, its hygroscopic and acidic nature contributes to the insufficient electrical conductivity, air stability and restricted photovoltaic (PV) performance for the fabricated PSCs. In this study, a new multifunctional additive, 2,3-dihydroxypyridine (DOH), has been used in the PEDOT: PSS buffer layer to obtain modified properties for PEDOT: PSS@DOH and achieve high PV performances. The electrical conductivity of PEDOT:PSS@DOH films was markedly improved compared with that of PEDOT:PSS. The PEDOT:PSS@DOH film exhibited excellent optical characteristics, appropriate work function alignment, and good surface properties in BHJ-PSCs. When a poly(3-hexylthiohpene):[6,6]-phenyl C₆₁-butyric acid methyl ester blend system was applied as the photoactive layer, the power conversion efficiency of the resulting PSCs with PEDOT:PSS@DOH(1.0%) reached 3.49%, outperforming pristine PEDOT:PSS, exhibiting a power conversion enhancement of 20%. The device fabricated using PEDOT:PSS@DOH (1.0 wt%) also exhibited improved thermal and air stability. Our results also confirm that DOH, a basic pyridine derivative, facilitates adequate hydrogen bonding interactions with the sulfonic acid groups of PSS, induces the conformational transformation of PEDOT chains and contributes to the phase separation between PEDOT and PSS chains.

We propose a design for a highly sensitive biosensor based on nanostructured anodized aluminum oxide (AAO) substrates. A gold-deposited AAO substrate exhibits both optical interference and localized surface plasmon resonance (LSPR). In our sensor, application of these disparate optical properties overcomes problems of limited sensitivity, selectivity, and dynamic range seen in similar biosensors. We fabricated uniform periodic nanopore lattice AAO templates by two-step anodizing and assessed their suitability for application in biosensors by characterizing the change in optical response on addition of biomolecules to the AAO template. To determine the suitability of such structures for biosensing applications, we immobilized a layer of C-reactive protein (CRP) antibody on a gold coating atop an AAO template. We then applied a CRP antigen (Ag) atop the immobilized antibody (Ab) layer. The shift in reflectance is interpreted as being caused by the change in refractive index with membrane thickness. Our results confirm that our proposed AAO-based biosensor is highly selective toward detection of CRP antigen, and can measure a change in CRP antigen concentration of 1 fg/ml. This method can provide a simple, fast, and sensitive analysis for protein detection in real-time.

We demonstrate the first-ever surface modification of green CdSe/ZnS quantum dots (QDs) using bromide anions (Br^-) in cetyl trimethylammonium bromide (CTAB). The Br^- ions reduced the interparticle spacing between the QDs and induced an effective charge balance in QD light-emitting devices (QLEDs). The fabricated QLEDs exhibited efficient charge injection because of the reduced emission quenching effect and their enhanced thin film morphology. As a result, they exhibited a maximum luminance of 71,000 cd/m² and an external current efficiency of 6.4 cd/A, both significantly better than those of their counterparts with oleic acid surface ligands. In addition, the lifetime of the Br- treated QD based QLEDs is significantly improved due to ionic passivation at the QDs surface.

In our study, we propose fast, highly sensitive, and wide-dynamic-range fiber-optic probe-type biosensors to detect pH and glucose. The operation principle of the proposed biosensors is based on the Fabry–Perot interferometry technique. Three pH-sensitive dyes (methyl orange, methyl red, and thymol blue) and three solvatochromic dyes (Nile red, rhodamine-B, and 4-amino-N-methylphthalimide (4-ANMP)) were individually mixed with polymers to obtain five pH-and three glucose-sensitive sensing membranes. These membranes were subsequently deposited on eight gold nanoparticles coated on fiber-optic probes to obtain five pH and three glucose fiber-optic probe sensors. To ascertain the effectiveness of the sensors, various concentrations of pH buffer solutions and glucose solutions were tested. The proposed fiber-optic pH and glucose probe sensors showed sensitivities of 1.95 nm/pH and 3.25 nm/mM, respectively, with high sensing stability with the relative standard deviation (RSD) about 2.5 %. The proposed sensors offer a linear sensing ability over wide ranges of pH (2–12) and glucose (1 μM–1M) with an R 2 value of approximately 0.996. The response and recovery times of the proposed sensors were approximately 8 s and 9 s, respectively. Finally in our study, we compared the performance of the proposed fiber-optic probe sensors with that of other pH and glucose sensors and determined that the proposed sensors achieve better sensing performance.

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