Enhanced Power-Conversion Efficiency in Inverted Bulk Heterojunction Solar Cells using Liquid-Crystal-Conjugated Polyelectrolyte Interlayer

Chao Liu; Yun Tan; Chunquan Li; Feiyan Wu; Lie Chen; Yiwang Chen

doi:10.1021/acsami.5b03340

Enhanced Power-Conversion Efficiency in Inverted Bulk Heterojunction Solar Cells using Liquid-Crystal-Conjugated Polyelectrolyte Interlayer

ACS Appl Mater Interfaces. 2015 Sep 2;7(34):19024-33. doi: 10.1021/acsami.5b03340. Epub 2015 Aug 24.

Authors

Chao Liu¹, Yun Tan¹, Chunquan Li², Feiyan Wu¹, Lie Chen^{1

3}, Yiwang Chen^{1

3}

Affiliations

¹ College of Chemistry/Institute of Polymers, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.
² Department of Electronic Information Engineering, Nanchang University, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.
³ Jiangxi Provincial Key Laboratory of New Energy Chemistry, Nanchang University , 999 Xuefu Avenue, Nanchang 330031, China.

PMID: 26280810
DOI: 10.1021/acsami.5b03340

Abstract

Two novel liquid-crystal-conjugated polyelectrolytes (LCCPEs) poly[9,9-bis[6-(4-cyanobiphenyloxy)-hexyl]-fluorene-alt-9,9-bis(6-(N,N-diethylamino)-hexyl)-fluorene] (PF6Ncbp) and poly[9,9-bis[6-(4-cyanobiphenyloxy)-hexyl]-fluorene-alt-9,9-bis(6-(N-methylimidazole)-hexyl]-fluorene] (PF6lmicbp) are obtained by covalent linkage of the cyanobiphenyl mesogen polar groups onto conjugated polyelectrolytes. After deposition a layer of LCCPEs on ZnO interlayer, the spontaneous orientation of liquid-crystal groups can induce a rearrangement of dipole moments at the interface, subsequently leading to the better energy-level alignment. Moreover, LCCPEs favors intimate interfacial contact between ZnO and the photon harvesting layer and induce active layer to form the nanofibers morphology for the enhancement of charge extraction, transportation and collection. The water/alcohol solubility of the LCCPEs also enables them to be environment-accepted solvent processability. On the basis of these advantages, the poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C60-butyric acid methyl ester (PC60BM)-based inverted polymer solar cells (PSCs) combined with ZnO/PF6Ncbp and ZnO/PF6lmicbp bilayers boost the power conversion efficiency (PCE) to 3.9% and 4.2%, respectively. Incorporation of the ZnO/PF6lmicbp into the devices based on a blend of a narrow band gap polymer thieno[3,4-b]thiophene/benzodithiophene (PTB7) with [6,6]-phenyl C70-butyric acid methyl ester (PC71BM) affords a notable efficiency of 7.6%.

Keywords: conjugated polyelectrolytes; interfacial modification; inverted devices; liquid crystal; polymer solar cells.

Publication types

Research Support, Non-U.S. Gov't