Document Type

Thesis - Open Access

Award Date

2020

Degree Name

Master of Science (MS)

Department / School

Electrical Engineering and Computer Science

First Advisor

Qiquan Qiao

Keywords

Atomic Force Microscopy, grain boundary, High Efficiency, passivation, perovskite solar cells, Triple Cation Perovskite

Abstract

Rigorous research on perovskite solar cell for more than ten years all over the world has led the rapid development of perovskite technology giving us device efficiency of 25.2%, surpassing the performance of traditional thin-film solar technologies on small scale devices (<1cm2). Perovskite material has excellent electronic and optical properties making it greatly suitable for PV application. The device fabrication process being simple with low cost and solution processability has led the researchers to visualize high efficiency scalable devices. Due to solution process fabrication method the defects in the materials causes the devices perform less than anticipated. These defects at the absorber material can come through as grain boundaries, surface defects, interfacial mismatch thus reducing photocurrent, open circuit voltage, fill factor and device stability. However, efforts and concentration has been highly directed on diminishing these detrimental defects from the perovskite crystals. Passivation engineering like interface interlayers, 2D perovskites, 2D/3D hybrid perovskites, secondary layers, grain engineering have been reported as a retaliation to minimize defects. Motivated by the outcomes of these works, a simple secondary growth of passivation layer on top of perovskite surface at the hole transport layer interface is studied here in this work showing enhanced device performance resulted from the treatment. Optical, surface morphological and different electronic study on both perovskite films and perovskite devices have been extensively studied and presented in this work to reveal the properties of the grain boundaries in triple cation mixed perovskite materials for simple planar n-i-p devices. With the secondary treatment of post perovskite deposition, the device performance enhanced to 20.6% efficiency from the control device efficiency of 17.4%, short circuit current density increased from 21.71 mA/cm2 to 24.49 mA/cm2, open circuit voltage improved to 1.13V from 1.11V and fill factor rallied to 0.75 from 0.72. Overall, this study provides elaborate in depth understanding on the grain boundaries, their detrimental effects, and successful passivating route to improve device performance.

Library of Congress Subject Headings

Perovskite solar cells.
Grain boundaries.
Photovoltaic power generation.

Format

application/pdf

Number of Pages

117

Publisher

South Dakota State University

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Rights Statement

In Copyright