| PhD Viva

Name of the Speaker: Mr. Rajdeep Dhar (EE15D310)
Guide: Dr. Soumya Dutta
Co-Guide: Dr. Venkatakrishnan P
Venue: Online
Online meeting link: meet.google.com/aea-zpgx-ypg
Date/Time: 8th July 2024(Monday), at 10.30AM
Title: DEVELOPMENT AND ANALYSIS OF ORGANIC SEMICONDUCTOR BASED BULK-HETEROJUNCTION DEVICES

Abstract :

The primary subject of interest for the PhD defence presentation will be bulk-heterojunction devices and methods for enhancing device performance. First, the development and study of UV-OPDs based on tetramethoxy π-expanded fluorene derivative (TMD), a small molecule donor, will be briefed. Here, the Chemistry Department at IIT Madras synthesized the previously mentioned small molecule. The device fabrication to obtain figures of merit like responsivity, specific detectivity and photosensitivty of 6 × 10−2 A/W, 9.36 × 1011 Jones and 105 order of magnitude, respectively, will also be discussed. Secondly, in order to enhance the interpenetrating bicontinuous network of donor and acceptor materials throughout the bulk of the thin film, solvent additive techniques and annealing approach will also be highlighted. Specifically, the enhancement on the power conversion efficiency of OPV devices with the addition of solvent additives such diphenyl sulphide (DPS) and diphenyl sulphoxide (DPSO) (DPSO was synthesized in the Chemistry Department, IIT Madras) and corresponding annealing techniques will be shown. In fine, a preliminary overview of the ambipolar charge carrier appearance in metal-insulator-semiconductor capacitor devices based on BHJ semiconductors will be presented for the first time. The emergence of unipolar and ambipolar capacitance-voltage characteristics can be considered as a diagnostic technique to predict the devices' operation through ambipolar charge transport, depending on the blend ratio.