Ph. D. THESIS COLLOQUIUM
Name: Mr. Suraj Yadav
Title: “Optimizing Light Absorption and Nanomorphology in Organic Solar Cells and Near-IR Photodetectors with Ternary Blend Approaches “
Date & Time : Monday, 28th October 2024 at 4.00 p.m.
Venue: Rajarshi Bhattacharya Memorial Lecture Hall, Chemical Sciences Building
Abstract:
Organic solar cells (OSCs) are a promising renewable energy solution due to their solution-processable, roll-to-roll fabrication, semitransparency, lightweight, and flexibility. Significant efforts have been focused on designing efficient electron-donating polymers and non-fullerene acceptors to improve power conversion efficiency (PCE) of OSCs. Despite recent advancements that led to PCE surpassing 20%, OSCs still trail behind silicon and perovskite solar cells in overall efficiency1 . The active layer, composed of a donor-acceptor mixture, suffers from many challenges, such as limited absorption coverage within the solar spectrum, uncontrolled nanomorphology, and high nonradiative recombination losses. Interestingly, the ternary blend approach offers a way to address the narrow-band absorption issue, and along with that, it also affects the nanomorphology. This demands the rational approach to choose a third component to optimize both nanomorphology and light absorption2 .
In my thesis, I have judiciously investigated the selection of a third component in binary blend OSCs, highlighting its benefits such as enhanced light harvesting, improved shortcircuit current density (JSC), and tunable open-circuit voltage (VOC) through energy level alignment and reduced recombination losses. We demonstrated how the inclusion of linearly linked perylene diimide (PDI) chromophores impacts the bulk heterojunction morphology, leading to enhanced device performance3,4.
Additionally, I studied the critical role of interface modification in charge extraction, showing how it helps to minimize recombination losses. By optimizing the interface, we significantly reduced non-radiative recombination losses5 .
Lastly, with the improved nanomorphology of our ternary blend bulk heterojunction, I observed suppressed dark current density and enhanced photodetection in near-IR photodetectors.
References:
(1) Li, Y.; Huang, W.; Zhao, D.; Wang, L.; Jiao, Z.; Huang, Q.; Wang, P.; Sun, M.; Yuan, G. Recent Progress in Organic Solar Cells: A Review on Materials from Acceptor to Donor. Mol. 2022, 27 (6), 1800.
(2) Ji, Y.; Xu, L.; Hao, X.; Gao, K. Energy Loss in Organic Solar Cells: Mechanisms, Strategies, and Prospects. Sol. RRL 2020, 4 (7), 2000130.
(3) Yadav, S.; Shivanna, R.; Mohapatra, A. A.; Sawhney, N.; Gangadharappa, C.; Swaraj, S.; Rao, A.; Friend, R. H.; Patil, S. Resonant Energy Transfer-Mediated Efficient Hole Transfer in the Ternary Blend Organic Solar Cells. J. Phys. Chem. Lett. 2023, 14 (29), 6601–6609.
(4) Yadav, S.; Pranav, M.; Gangadharappa, C.; Huss-Hansen, M.; Schwartzkopf, M.; Kjelstrup-Hansen, J.; Knaapila, M.; Patil, S. Rational Third Component Choices Drive Enhanced Morphology and Efficiency in Ternary Blend Organic Solar Cells. ACS Energy Lett. 2024, 9 (10), 5259–5267.
(5) Mohapatra, A. A.; Pranav, M.; Yadav, S.; Gangadharappa, C.; Wu, J.; Labanti, C.; Wolansky, J.; Benduhn, J.; Kim, J.; Durrant, J.; Patil, S. Interface Engineering in Perylene Diimide-Based Organic Photovoltaics with Enhanced Photovoltage. ACS Appl. Mater. Interfaces 2023, 15 (21), 25224–25231.