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I fabricate and characterise bulk heterojunction organic solar cells with interfacial layer engineer

I work in the field of bulk heterojunction organic solar cells, a hot field currently discussed all over the world, where I study the fundamental processes in polymer- based solar cells, the role of interfacial layers in charge extraction and recombination. We, in our lab, fabricate different inverted structures using polymer-fullerene blends, engineer interfacial layers and do studies in photocurrent carriers, recombination mechanisms etc. Studies on charge generation in bulk heterojunction solar cell using different interfacial layers are also carried out. One of the structures fabricated in the air has got a high efficiency of 9.1% with a good fill factor (Journal of Physical Chemistry C (DOI:10.1021/acs.jpcc.7b01314)). I also work on plasmonic solar cells, which has got some good results of 5.46% in the bulk heterojunction solar cell. The effect of different shape and size of metal nanoparticles in various layers of the organic solar cell are also studied. I also have expertise in analyzing UV-visible absorption spectra, scanning electron microscopy (SEM) images, atomic force microscopy (AFM) images and X-Ray diffraction (XRD) patterns.


Effect of Dual Cathode Buffer Layer on the Charge Carrier Dynamics of rrP3HT:PCBM Based Bulk Heterojunction Solar Cell

Abstract: In bulk heterojunction (BHJ) solar cells, the buffer layer plays a vital role in enhancing the power conversion efficiency (PCE) by improving the charge carrier dynamics. A comprehensive understanding of the contacts is especially essential in order to optimize the performance of organic solar cells (OSCs). Although there are several fundamental reports on this subject, a proper correlation of the physical processes with experimental evidence at the photoactive layer and contact materials is essential. In this work, we incorporated three different additional buffer layers, namely, tris(8-hydroxyquinolinato) aluminum (Alq3), bathophenanthroline (BPhen) or bathocuproine (BCP) with LiF/Al as conventional cathode contact in both rrP3HT:PC61BM and rrP3HT:PC71BM blend BHJ solar cells and their corresponding photovoltaic performances were systematically correlated with their energy level diagram. The device with dual cathode buffer layer having ITO/PEDOT:PSS/blend polymer/BCP/LiF/Al configuration showed the best device performance with PCE, η = 4.96%, Jsc = 13.53 mA/cm2, Voc = 0.60 V and FF= 61% for rrP3HT:PC71BM and PCE, η = 4.5% with Jsc = 13.3 mA/cm2, Voc = 0.59 V and FF = 59% for rrP3HT:PC61BM. This drastic improvement in PCE in both the device configurations are due to the combined effects of better hole-blocking capacity of BCP and low work function provided by LiF/Al with the blend polymer. These results successfully explain the role of dual cathode buffer layers and their contribution to the PCE improvement and overall device performance with rrP3HT:PCBM based BHJ solar cell.

Pub.: 14 Apr '16, Pinned: 01 Jul '17

Ligand-free attachment of plasmonic Au nanoparticles on ZnO nanowire to make a high-performance broadband photodetector using a laser-based method.

Abstract: We report a new strategy for ligand-free attachment of plasmonic Au nanoparticles on the surface of a ZnO nanowire to make high-performance broadband photodetectors using a pulsed laser ablation technique in a liquid medium. The photoresponse of the ZnO-based photodetector is enhanced and the photodetection limit is broadened from UV to visible, which can be controlled by varying the concentration of Au nanoparticles attached to the ZnO surface. This Au nanoparticle concentration can be tuned by varying the number of laser pulses used in the ablation process. We found that the responsivity of the detector is 10 mA W(-1) for [Formula: see text] and increases to as much as 0.4 A W(-1) for λ ≤ 400 nm for the maximum Au concentration. The enhanced responsivity was found to be linked to increased absorption over a broad spectral range arising from direct and indirect plasmonic processes due to Au nanoparticle attachment, and the enhanced absorption also leads to a large increment in photocurrent generation. We also found that the attachment of Au nanoparticles makes the relaxation of the photocurrent (persistence) considerably faster in both the UV and visible regions of the spectrum and that the persistence directly depends on the concentration of Au nanoparticles attached to the ZnO nanowire. This single-step pulsed laser ablation-based nanoparticle attachment process can be further used to make other plasmonic nanoparticle-decorated nanowire devices.

Pub.: 29 Jun '17, Pinned: 01 Jul '17