• Energy Research

Abstract The cooperative effect of hybrid Au-Ag nanoparticles and organic-inorganic cathode interfacial layers to advance the power conversion efficiency (PCE) of regio regular (rr) P3HT:PCBM based polymer solar cells (PSCs) are systematically demonstrated. In this work initially, two types of plasmonic nanoparticles (NPs), namely, citrate stabilized gold (AuNPs) and silver (AgNPs) were separately synthesized and then physically blend together with three different volume ratio [AuNPs + AgNPs (25:75), AuNPs + AgNPs (50:50) and AuNPs + AgNPs (75:25)]. These three blended NP solutions were then mixed together in the PEDOT:PSS (20 v/v %) hole extraction layer (HEL) to form three new NPs doped HEL and their effect on the rr-P3HT:PCBM based PSCs were systematically analyzed. For dual organic-inorganic cathode interfacial layers, two organic hole blocking materials, BPhen and BCP were used for enhanced charge collection in combination with LiF:Al as conventional cathode electrode. The collective effect of hybrid NPs with the dual cathode interfacial layers was examined with two varying active polymer blends, rr-P3HT:PC61BM and rr-P3HT:PC71BM. It has been found that the PCE increases considerably for both the active blend systems, with PEDOT:PSS + [AuNPs:AgNPs (25:75)] + BCP:LiF:Al as the modified cathode electrode. This is due to suitable electronic energy level matching of BCP:LiF:Al and active blend with the excellent surface plasmon property of the AuNPs:AgNPs (25:75) in the UV–Visible region compared to AuNPs:AgNPs (50:50) and AuNPs:AgNPs (75:25). Devices having configuration PEDOT:PSS + [AuNPs:AgNPs (25:75)] as HEL, rr-P3HT:PC71BM as active blend and BCP:LiF:Al provided PCE, ɳmax = 5.71% with Jsc = 16.44 mA/cm2, Voc = 0.58 V, FF = 60% and device with rr-P3HT:PC61BM as active blend layer was showing as PCE, ɳmax = 5.31% with Jsc = 14.77 mA/cm2, Voc = 0.58 V and FF = 62% with the same PEDOT:PSS + [AuNPs:AgNPs (25:75)] layer and BCP:LiF:Al. These results conclusively described a very simple technique in which the cooperative effect of plasmonic hybrid metals nanoparticles and dual cathode interfacial layers outstandingly enrich the PCE and in general the complete nature of rr-P3HT:PCBM based PSCs.

Three random terpolymers were synthesized by subtle incorporation of fluoroarenes as the third monomer into the popular PTB7-Th backbone and utilized for photovoltaic applications. By substituting 5% of 3-fluorothieno­[3,4- b ]­thiophene-2-carboxylate in the PTB7-Th backbone using monomers such as 2,5-difluorobenzene, 2,3-difluorobenzene, and 2,3,5,6-tetrafluorobenzene, random terpolymers M1, M2, and M3 were synthesized, respectively. The presence of fluorinated monomers deepened the highest occupied molecular orbital (HOMO) energy level of terpolymers, which substantially enhanced the open circuit voltage ( V OC ) of polymer solar cells (PSCs). The power conversion efficiency (PCE) for M1- and M2-based PSCs reached up to 9.48 and 8.80% from 8.19% for the PTB7-Th:PC 71 BM blend. However, M3-based blend exhibited an inferior PCE of 8.13% majorly due to its weaker absorption in the higher-wavelength region and lower carrier mobility. The M1 polymer also exhibited an enhanced PCE of 9.01% compared to 7.68% for PTB7-Th with ITIC, a non-fullerene acceptor. Moreover, the fluoroarenes induced intra/intermolecular non-covalent interactions in blend films. These interactions acted as a conformational lock to tune the morphology that also improved the phase domain stability. M1:PC 71 BM-based PSC displayed superior capability to sustain under ambient conditions and it retained 82% of its initial PCE after 1000 h of ambient exposure in comparison to 51% of the PTB7-Th blend under a relative humidity of 45 ± 5%. This generic approach can be utilized in finely modulating the property of photovoltaic materials to enhance the performance along with the stability of PSCs.

The growth of smart wearable sensing systems has gained immense importance in the present mode of data acquisition and signaling in pharmaceutical, healthcare, and wellness industries. Presently, application of smart wearables is gaining prominence in several fitness activities, therapeutics, and diagnostic areas. Smart wearable biosensors offer real-time monitoring of physiological metrics and biomarkers that are specific to certain diseases in ambulant condition. This review offers a broad overview of the state-of-the-art progress on smart wearable biosensors focusing on applications in point of care diagnostics. A careful comparison of presently available commercial devices, implementation in clinical trials, and validation also have been highlighted in the present review. This work concludes with challenges and future prospects for scientists and engineers working in the nascent interdisciplinary field.

Fabrication of high performance polymer solar cells using a ternary polymer system modulates the morphology of the active layer, and significantly enhances the Voc, Jsc, PCE and mobility values.