Sains Malaysiana 49(11)(2020): 2821-2832 http://dx.doi.org/10.17576/jsm-2020-4911-21 First-Principles Study of Structural, Electronic and Thermoelectric Properties of Ni- Doped Bi 2 Se 3 (Kajian Prinsip Pertama tentang Sifat Struktur, Elektronik dan Termoelektrik bagi Bi 2 Se 3 Ni-Terdop) MUHAMMAD ZAMIR MOHYEDIN, MOHAMAD FARIZ MOHAMAD TAIB*, AFIQ RADZWAN, MASNAWI MUSTAFFA, AMIRUDDIN SHAARI, BAKHTIAR UL-HAQ, OSKAR HASDINOR HASSAN & MUHD ZU AZHAN YAHYA ABSTRACT Direct conversion of waste heat to electrical energy could address present energy challenges. Bi 2 Se 3 is one of few thermoelectric materials known to operate at room temperature. Comprehensive analysis using density functional theory was conducted to explore the efect of nickel doping on structural, electronic, and thermoelectric properties of Bi 2 Se 3 . Local density approximation (LDA) was used with an addition of spin-orbit coupling (SOC) and van der Waals interaction scheme consideration. Analysis of the efect of SOC was elaborated. It was found that nickel has changed the crystal structure of Bi 2 Se 3 . Nickel has also changed band structure and density of state that alter the thermoelectric performance. The decreased band gap has decreased the thermopower. However, it gives advantages to the improvement of electrical conductivity. Higher electrical conductivity has risen thermal conductivity. Despite the decreased thermopower and increased thermal conductivity, the higher electrical conductivity has improved the overall thermoelectric performance of Bi 2 Se 3 when nickel is introduced. Keywords: Density functional theory; electrical conductivity; electronic properties; spin-orbit coupling; thermoelectricity ABSTRAK Penukaran sisa haba kepada tenaga elektrik dapat menangani cabaran tenaga yang ada pada masa ini. Bi 2 Se 3 adalah salah satu daripada beberapa bahan termoelektrik yang diketahui mampu beroperasi pada suhu bilik. Analisis komprehensif menggunakan teori ketumpatan berfungsi telah dijalankan untuk meneroka kesan pendopan nikel pada sifat struktur, elektronik dan termoelektrik Bi 2 Se 3 . Penghampiran ketumpatan setempat (PKS) digunakan dengan mempertimbangkan penambahan gandingan spin-petala (GSP) dan skema interaksi van der Waals. Analisis kesan GSP dijelaskan. Didapati bahawa nikel telah mengubah struktur kristal Bi 2 Se 3 . Nikel juga telah menukar struktur jalur dan ketumpatan keadaan yang mengubah prestasi termoelektrik. Penurunan jurang jalur telah menurunkan termokuasa. Walau bagaimanapun, ia memberi kelebihan kepada peningkatan kekonduksian elektrik. Kekonduksian elektrik yang tinggi telah meningkatkan kekonduksian terma. Walaupun termokuasa menurun dan kekonduksian terma meningkat, kekonduksian elektrik yang lebih tinggi telah meningkatkan prestasi termoelektrik keseluruhan Bi 2 Se 3 apabila nikel diperkenalkan. Kata kunci: Gandingan spin-petala; kekonduksian elektrik; sifat elektronik; teori ketumpatan berfungsi; termoelektrik INTRODUCTION Thermoelectric materials have received wide attention due to its ability to convert waste heat to electricity especially some of the materials that can effectively operating at room temperature (Bashir et al. 2018; Hasan et al. 2018). It could also potentially become one of the solutions for energy and environmental crisis like global warming (Saeed et al. 2014b). Its high-performance provides a great contribution to the society for its application in thermoelectric refrigeration (Mishra et al. 1997), radiation detector (Augustine et al. 2003) and environmental protector (Saeed et al. 2014b). The performance of thermoelectric material can be described by a dimensionless fgure of merit (ZT): where S is the Seebeck Efect or thermopower; σ is electrical conductivity; T is the temperature; and κ  =  2  