Student Seminar
Name: Mr. Anuj Kumar Palariya
Title: Transparent top-contact for optoelectronic devices
Date & Time: Thursday, 30th October 2025 at 4.00 p.m.
Venue: Rajarshi Bhattacharyya Memorial Lecture Hall, Chemical Sciences Building
Abstract:
Transparent electrodes are indispensable as top contacts in photovoltaic and optoelectronic devices because they must balance high optical transmittance with low electrical resistance to maximize both light harvesting and charge collection (1, 2). Their design typically involves materials such as transparent conductive oxides (e.g., ITO, AZO), ultrathin metal films, silver nanowires, carbon nanotubes, graphene, and conductive polymers like PEDOT:PSS, each offering unique trade‐offs in terms of conductivity, flexibility, and cost (3). ITO remains prevalent due to its excellent transparency and conductivity, yet its brittleness and high processing temperature drive research toward alternative materials that favor flexible device architectures (2, 4).
Composite architectures such as dielectric–metal–dielectric stacks or mesh-like metal grids have been developed to achieve transmittance levels exceeding 90% with sheet resistances below 10 Ω/sq, which are essential for top-contact performance in applications like solar cells and OLEDs (5, 4). Scalable fabrication approaches—including spin coating, spray coating, and inkjet printing—enable solution processing on flexible substrates, while modifications in work function and surface morphology through doping or interlayer engineering help maintain interfacial stability (4). Challenges remain in ensuring uniform film deposition, chemical stability at the electrode/active layer interface, and robust adhesion under operational conditions (6). Future research is focused on integrating novel material combinations and fabrication techniques to further improve both the optical and electrical performance of transparent top contacts (6, 2).
References:
Huseynova, G.; Lee, J.-H.; Kim, Y. H.; Lee, J. Transparent Organic Light‐Emitting Diodes: Advances, Prospects, and Challenges. Adv. Opt. Mater. 2021, DOI: 10.1002/adom.202002040.
Morales‐Masis, M.; De Wolf, S.; Woods‐Robinson, R.; Ager, J. W.; Ballif, C. Transparent Electrodes for Efficient Optoelectronics. Adv. Electron. Mater. 2017.
Zhang, Y.; Ng, S.-W.; Lu, X.; Zheng, Z. Solution-Processed Transparent Electrodes for Emerging Thin-Film Solar Cells. Chem. Rev. 2020, 120, 2049–2122, DOI: 10.1021/acs.chemrev.9b00483.
Chang, S.-Y.; Cheng, P.; Li, G.; Yang, Y. Transparent Polymer Photovoltaics for Solar Energy Harvesting and Beyond. Joule 2018, 2, 1039–1054, DOI: 10.1016/j.joule.2018.04.005.
Liu, L.; Cao, K.; Chen, S.; Huang, W. Toward See‐Through Optoelectronics: Transparent Light‐Emitting Diodes and Solar Cells. Adv. Opt. Mater. 2020, DOI: 10.1002/adom.202001122.
Nguyen, V. H.; Papanastasiou, D. T.; Resende, J.; Bardet, L.; Sannicolo, T.; Jiménez, C.; Muñoz‐Rojas, D.; Nguyen, N. D.; Bellet, D. Advances in Flexible Metallic Transparent Electrodes. Small 2022, 18, e2106006, DOI: 10.1002/smll.202106006.