Engineering and Investigation of Zinc Oxide Cathode Interfacial Layer in Inverted Organic Solar Cells: Implications for Charge Transport and Collection | Shiv Nadar University
Enquire Now
Apply Now
Undergraduate AdmissionsPhD Admissions Spring 2023MBA Admissions 2023MBA Information Session

Engineering and Investigation of Zinc Oxide Cathode Interfacial Layer in Inverted Organic Solar Cells: Implications for Charge Transport and Collection

The aim of my thesis is to investigate and engineer Zinc oxide (ZnO) cathode buffer layer (CBL) which bridges the transparent electrode and the active layer in an inverted organic solar cell (OSC). We have used current density-voltage (J-V), space charge limited current (SCLC), capacitance-voltage (C-V) and impedance spectroscopy (IS) techniques to study charge transport, charge carrier recombination and charge collection efficiency in devices. A quantitative and qualitative analysis of the structural and surface aspects of sol-gel processed ZnO was done using X-ray reflectivity (XRR) and atomic force microscopy (AFM) techniques. On the basis of our understanding of the structural-property-performance correlation in the sol-gel processed ZnO based inverted OSCs, we developed an approach to engineer the ZnO layer by using an alternate precursor, Diethyl Zinc (DEZ). Further, with the same precursor, we developed a PC61BM doped ZnO-organic hybrid cathode buffer layer and implemented in OSCs. We have investigated a self-assembled approach for realizing an ideal p-i-n structure in conjunction with ZnO buffer layers in inverted OSCs. We used a specifically designed ternary bulk-heterojunction (BHJ) active layer involving one donor (PTB7-Th) and two structurally different acceptor molecules, an ellipsoidal PC71BM, and a spherical PC61BM. The inverted OSCs having the ternary active layer with ZnO cathode buffer layer are investigated to understand the impact of these improvisations on the electron transport and their collection. Further, we have interpreted the improved device performances and their electrical characteristics in the context of structural and chemical changes occurred in ZnO buffer layer and at their interfaces.
In summary, we have proposed and discussed a cohesive interface engineering in OSCs based on self-assembled and artificially modified ZnO/BHJ interfaces, which could be an ideal approach to improve OPV devices performances and stability.
 

Department: 
Physics
Year: 
2018
Student Name: 
Shashi Bhushan Srivastava
Faculty Advisor: 

Directions