Correlation between Photovoltaic Performance and Interchain Ordering Induced Delocalization of Electronics States in Conjugated Polymer Blends

Naresh Chandrasekaran, Eliot Gann, Nakul Jain, Anshu Kumar, Sreelekha Gopinathan, Aditya Sadhanala, Richard H. Friend, Anil Kumar, Christopher R. McNeill, Dinesh Kabra

Research output: Contribution to journalArticleResearchpeer-review

Abstract

In this paper we correlate the solar cell performance with bimolecular packing of donor:acceptor bulk heterojunction (BHJ) organic solar cells (OSCs), where interchain ordering of the donor molecule and its influence on morphology, optical properties, and charge carrier dynamics of BHJ solar cells are studied in detail. Solar cells that are fabricated using more ordered defect free 100% regioregular poly(3-hexylthiophene) (DF-P3HT) as the donor polymer show ca. 10% increase in the average power conversion efficiency (PCE) when compared to that of the solar cell fabricated using 92% regioregularity P3HT, referred to as rr-P3HT. EQE and UV-vis absorption spectrum show a clear increase in the 607 nm vibronic shoulder of the DF-P3HT blend suggesting better interchain ordering which was also reflected in the less Urbach energy (Eu) value for this system. The increase in ordering inside the blend has enhanced the hole-mobility which is calculated from the single carrier device J-V characteristics. Electroluminance (EL) studies on the DF-P3HT system showed a red-shifted peak when compared to rr-P3HT-based devices suggesting low CT energy states in DF-P3HT. The morphologies of the blend films are studied using AFM and grazing-incidence wide-angle X-ray scattering (GIWAXS) suggesting increase in the roughness and phase segregation which could enhance the internal scattering of the light inside the device and improvement in the crystallinity along alkyl and π-stacking direction. Hence, higher PCE, lower Eu, red-shifted EL emission, high hole-mobility, and better crystallinity suggest improved interchain ordering has facilitated a more delocalized HOMO state in DF-P3HT-based BHJ solar cells.

Original languageEnglish
Pages (from-to)20243-20250
Number of pages8
JournalACS Applied Materials and Interfaces
Volume8
Issue number31
DOIs
Publication statusPublished - 10 Aug 2016

Keywords

  • charge carrier dynamics
  • defect free P3HT
  • interchain order
  • morphology
  • organic solar cells

Cite this

Chandrasekaran, Naresh ; Gann, Eliot ; Jain, Nakul ; Kumar, Anshu ; Gopinathan, Sreelekha ; Sadhanala, Aditya ; Friend, Richard H. ; Kumar, Anil ; McNeill, Christopher R. ; Kabra, Dinesh. / Correlation between Photovoltaic Performance and Interchain Ordering Induced Delocalization of Electronics States in Conjugated Polymer Blends. In: ACS Applied Materials and Interfaces. 2016 ; Vol. 8, No. 31. pp. 20243-20250.
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abstract = "In this paper we correlate the solar cell performance with bimolecular packing of donor:acceptor bulk heterojunction (BHJ) organic solar cells (OSCs), where interchain ordering of the donor molecule and its influence on morphology, optical properties, and charge carrier dynamics of BHJ solar cells are studied in detail. Solar cells that are fabricated using more ordered defect free 100{\%} regioregular poly(3-hexylthiophene) (DF-P3HT) as the donor polymer show ca. 10{\%} increase in the average power conversion efficiency (PCE) when compared to that of the solar cell fabricated using 92{\%} regioregularity P3HT, referred to as rr-P3HT. EQE and UV-vis absorption spectrum show a clear increase in the 607 nm vibronic shoulder of the DF-P3HT blend suggesting better interchain ordering which was also reflected in the less Urbach energy (Eu) value for this system. The increase in ordering inside the blend has enhanced the hole-mobility which is calculated from the single carrier device J-V characteristics. Electroluminance (EL) studies on the DF-P3HT system showed a red-shifted peak when compared to rr-P3HT-based devices suggesting low CT energy states in DF-P3HT. The morphologies of the blend films are studied using AFM and grazing-incidence wide-angle X-ray scattering (GIWAXS) suggesting increase in the roughness and phase segregation which could enhance the internal scattering of the light inside the device and improvement in the crystallinity along alkyl and π-stacking direction. Hence, higher PCE, lower Eu, red-shifted EL emission, high hole-mobility, and better crystallinity suggest improved interchain ordering has facilitated a more delocalized HOMO state in DF-P3HT-based BHJ solar cells.",
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author = "Naresh Chandrasekaran and Eliot Gann and Nakul Jain and Anshu Kumar and Sreelekha Gopinathan and Aditya Sadhanala and Friend, {Richard H.} and Anil Kumar and McNeill, {Christopher R.} and Dinesh Kabra",
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Correlation between Photovoltaic Performance and Interchain Ordering Induced Delocalization of Electronics States in Conjugated Polymer Blends. / Chandrasekaran, Naresh ; Gann, Eliot; Jain, Nakul; Kumar, Anshu; Gopinathan, Sreelekha; Sadhanala, Aditya; Friend, Richard H.; Kumar, Anil; McNeill, Christopher R.; Kabra, Dinesh.

In: ACS Applied Materials and Interfaces, Vol. 8, No. 31, 10.08.2016, p. 20243-20250.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Correlation between Photovoltaic Performance and Interchain Ordering Induced Delocalization of Electronics States in Conjugated Polymer Blends

AU - Chandrasekaran, Naresh

AU - Gann, Eliot

AU - Jain, Nakul

AU - Kumar, Anshu

AU - Gopinathan, Sreelekha

AU - Sadhanala, Aditya

AU - Friend, Richard H.

AU - Kumar, Anil

AU - McNeill, Christopher R.

AU - Kabra, Dinesh

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AB - In this paper we correlate the solar cell performance with bimolecular packing of donor:acceptor bulk heterojunction (BHJ) organic solar cells (OSCs), where interchain ordering of the donor molecule and its influence on morphology, optical properties, and charge carrier dynamics of BHJ solar cells are studied in detail. Solar cells that are fabricated using more ordered defect free 100% regioregular poly(3-hexylthiophene) (DF-P3HT) as the donor polymer show ca. 10% increase in the average power conversion efficiency (PCE) when compared to that of the solar cell fabricated using 92% regioregularity P3HT, referred to as rr-P3HT. EQE and UV-vis absorption spectrum show a clear increase in the 607 nm vibronic shoulder of the DF-P3HT blend suggesting better interchain ordering which was also reflected in the less Urbach energy (Eu) value for this system. The increase in ordering inside the blend has enhanced the hole-mobility which is calculated from the single carrier device J-V characteristics. Electroluminance (EL) studies on the DF-P3HT system showed a red-shifted peak when compared to rr-P3HT-based devices suggesting low CT energy states in DF-P3HT. The morphologies of the blend films are studied using AFM and grazing-incidence wide-angle X-ray scattering (GIWAXS) suggesting increase in the roughness and phase segregation which could enhance the internal scattering of the light inside the device and improvement in the crystallinity along alkyl and π-stacking direction. Hence, higher PCE, lower Eu, red-shifted EL emission, high hole-mobility, and better crystallinity suggest improved interchain ordering has facilitated a more delocalized HOMO state in DF-P3HT-based BHJ solar cells.

KW - charge carrier dynamics

KW - defect free P3HT

KW - interchain order

KW - morphology

KW - organic solar cells

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