Iodine Doping Studies on Nonannealed Perylene 3,4,9,10-Tetra Carboxylic Dianhydride/Cobalt Phthalocyanine Bulk Heterojunction Solar Cells

Priya A Hoskeri,Joseph C M,Ayachit N H,Gayathri A G

doi:10.1177/1943089213507021

Abstract

Perylene 3,4,9,10-tetra carboxylic dianhydride (PTCDA) thin films find a lot of optoelectronic applications. In this work, thin films of PTCDA were deposited using vacuum evaporation technique onto clean glass substrates and the variation in conductivity, optical bandgap and percentage transmission due to iodine doping for different time intervals are discussed. To study the doping effects on devices, organic solar cells based on cobalt phthalocyanine (CoPc)/PTCDA as active layers on indium tin oxide–coated glass substrates were fabricated and characterized to evaluate the solar cell parameters. It was found that doping with iodine considerably increases the power conversion efficiency of the solar cells.

Highlights

Organic semiconductors are expected to play a vital role in both industry and research in the coming years
We studied the doping effects of I2 on the electrical and device properties of cobalt phthalocyanine (CoPc)/PTCDA solar cells
Conductivity studies on doped and undoped PTCDA thin films showed that the conductivity increases from 7.6 Â 10À5 OÀ1 mÀ1 to a maximum of 2.8 Â 10À3 OÀ1 mÀ1 on doping

Summary

Introduction

Organic semiconductors are expected to play a vital role in both industry and research in the coming years. Perylene derivatives are commercially available as red pigments with electrical and optical properties that allow them to be compared with conventional inorganic wide bandgap semiconductors.[1,2] Recently, a lot of research were done on the study of the archetype molecular compound Perylene 3,4,9,10 tetracarboxylic dianhydride (PTCDA). The primary motivation for focusing on PTCDA is its promising optical and electronic properties.[3,4] The PTCDA films find optoelectronic applications and serve as a model substance for the investigation of thin organic film and possible future devices.[5,6,7] Electrical property studies of thin films are a subject of current interest, as they may lead to useful electronic devices. Transition metal-based phthalocyanines like cobalt phthalocyanine (CoPc) have attracted attention in the areas of fuel cells, gas sensors, biosensors, and electronic devices like driver transistors and solar cells.[8,9,10,11] For studying the doping effects on devices, CoPc active layers were used in the heterojunction

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