Limits for Recombination in a Low Energy Loss Organic Heterojunction

S. Matthew Menke; Aditya Sadhanala; Mark Nikolka; Niva A. Ran; Mahesh Kumar Ravva; Safwat Abdel-Azeim; Hannah L. Stern; Ming Wang; Henning Sirringhaus; Thuc-Quyen Nguyen; Jean-Luc Bredas; Guillermo C. Bazan; Richard H. Friend

doi:10.1021/acsnano.6b06211

Limits for Recombination in a Low Energy Loss Organic Heterojunction

S. Matthew Menke, Aditya Sadhanala, Mark Nikolka, Niva A. Ran, Mahesh Kumar Ravva, Safwat Abdel-Azeim, Hannah L. Stern, Ming Wang, Henning Sirringhaus, Thuc-Quyen Nguyen, Jean-Luc Bredas, Guillermo C. Bazan, Richard H. Friend

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Abstract

Donor-acceptor organic solar cells often show high quantum yields for charge collection, but relatively low open-circuit voltages (VOC) limit power conversion efficiencies to around 12%. We report here the behavior of a system, PIPCP:PC61BM, that exhibits very low electronic disorder (Urbach energy less than 27 meV), very high carrier mobilities in the blend (field-effect mobility for holes >10-2 cm2 V-1 s-1), and a very low driving energy for initial charge separation (50 meV). These characteristics should give excellent performance, and indeed, the VOC is high relative to the donor energy gap. However, we find the overall performance is limited by recombination, with formation of lower-lying triplet excitons on the donor accounting for 90% of the recombination. We find this is a bimolecular process that happens on time scales as short as 100 ps. Thus, although the absence of disorder and the associated high carrier mobility speeds up charge diffusion and extraction at the electrodes, which we measure as early as 1 ns, this also speeds up the recombination channel, giving overall a modest quantum yield of around 60%. We discuss strategies to remove the triplet exciton recombination channel.

Original language	English (US)
Pages (from-to)	10736-10744
Number of pages	9
Journal	ACS Nano
Volume	10
Issue number	12
DOIs	https://doi.org/10.1021/acsnano.6b06211
State	Published - Nov 3 2016

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: S.M.M., R.H.F., M.K.R., S.A.-A., and J.-L.B. acknowledge support from the KAUST Competitive Research Grant Program. M.K.R., S.A.-A., and J.-L.B. also acknowledge generous support of their work by KAUST and the Office of Naval Research Global (Award N629091512003); they thank the KAUST IT Research Computing Team and Supercomputing Laboratory for providing computational and storage resources. N.A.R., M.W., T.-Q.N., and G.C.B. acknowledge support from the Department of the Navy, Office of Naval Research (Award Nos. N00014-14-1-0580 and N00014-16-1-25200. A.S. would like to acknowledge the funding and support from the India–UK APEX project. H.L.S. acknowledges support from the Winton Programme for the Physics of Sustainability. M.N. and H.S. gratefully acknowledge financial support from the Engineering and Physical Sciences Research Council though a Programme Grant (EP/M005141/1).

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10.1021/acsnano.6b06211

https://repository.kaust.edu.sa/bitstream/10754/622740/1/acsnano2E6b06211.pdf

Cite this

@article{ab6f57b361fd42bd8fa394d9e91a2c2e,

title = "Limits for Recombination in a Low Energy Loss Organic Heterojunction",

abstract = "Donor-acceptor organic solar cells often show high quantum yields for charge collection, but relatively low open-circuit voltages (VOC) limit power conversion efficiencies to around 12%. We report here the behavior of a system, PIPCP:PC61BM, that exhibits very low electronic disorder (Urbach energy less than 27 meV), very high carrier mobilities in the blend (field-effect mobility for holes >10-2 cm2 V-1 s-1), and a very low driving energy for initial charge separation (50 meV). These characteristics should give excellent performance, and indeed, the VOC is high relative to the donor energy gap. However, we find the overall performance is limited by recombination, with formation of lower-lying triplet excitons on the donor accounting for 90% of the recombination. We find this is a bimolecular process that happens on time scales as short as 100 ps. Thus, although the absence of disorder and the associated high carrier mobility speeds up charge diffusion and extraction at the electrodes, which we measure as early as 1 ns, this also speeds up the recombination channel, giving overall a modest quantum yield of around 60%. We discuss strategies to remove the triplet exciton recombination channel.",

author = "Menke, {S. Matthew} and Aditya Sadhanala and Mark Nikolka and Ran, {Niva A.} and Ravva, {Mahesh Kumar} and Safwat Abdel-Azeim and Stern, {Hannah L.} and Ming Wang and Henning Sirringhaus and Thuc-Quyen Nguyen and Jean-Luc Bredas and Bazan, {Guillermo C.} and Friend, {Richard H.}",

note = "KAUST Repository Item: Exported on 2020-10-01 Acknowledgements: S.M.M., R.H.F., M.K.R., S.A.-A., and J.-L.B. acknowledge support from the KAUST Competitive Research Grant Program. M.K.R., S.A.-A., and J.-L.B. also acknowledge generous support of their work by KAUST and the Office of Naval Research Global (Award N629091512003); they thank the KAUST IT Research Computing Team and Supercomputing Laboratory for providing computational and storage resources. N.A.R., M.W., T.-Q.N., and G.C.B. acknowledge support from the Department of the Navy, Office of Naval Research (Award Nos. N00014-14-1-0580 and N00014-16-1-25200. A.S. would like to acknowledge the funding and support from the India–UK APEX project. H.L.S. acknowledges support from the Winton Programme for the Physics of Sustainability. M.N. and H.S. gratefully acknowledge financial support from the Engineering and Physical Sciences Research Council though a Programme Grant (EP/M005141/1).",

year = "2016",

month = nov,

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doi = "10.1021/acsnano.6b06211",

language = "English (US)",

volume = "10",

pages = "10736--10744",

journal = "ACS Nano",

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publisher = "American Chemical Society",

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TY - JOUR

T1 - Limits for Recombination in a Low Energy Loss Organic Heterojunction

AU - Menke, S. Matthew

AU - Sadhanala, Aditya

AU - Nikolka, Mark

AU - Ran, Niva A.

AU - Ravva, Mahesh Kumar

AU - Abdel-Azeim, Safwat

AU - Stern, Hannah L.

AU - Wang, Ming

AU - Sirringhaus, Henning

AU - Nguyen, Thuc-Quyen

AU - Bredas, Jean-Luc

AU - Bazan, Guillermo C.

AU - Friend, Richard H.

N1 - KAUST Repository Item: Exported on 2020-10-01 Acknowledgements: S.M.M., R.H.F., M.K.R., S.A.-A., and J.-L.B. acknowledge support from the KAUST Competitive Research Grant Program. M.K.R., S.A.-A., and J.-L.B. also acknowledge generous support of their work by KAUST and the Office of Naval Research Global (Award N629091512003); they thank the KAUST IT Research Computing Team and Supercomputing Laboratory for providing computational and storage resources. N.A.R., M.W., T.-Q.N., and G.C.B. acknowledge support from the Department of the Navy, Office of Naval Research (Award Nos. N00014-14-1-0580 and N00014-16-1-25200. A.S. would like to acknowledge the funding and support from the India–UK APEX project. H.L.S. acknowledges support from the Winton Programme for the Physics of Sustainability. M.N. and H.S. gratefully acknowledge financial support from the Engineering and Physical Sciences Research Council though a Programme Grant (EP/M005141/1).

PY - 2016/11/3

Y1 - 2016/11/3

N2 - Donor-acceptor organic solar cells often show high quantum yields for charge collection, but relatively low open-circuit voltages (VOC) limit power conversion efficiencies to around 12%. We report here the behavior of a system, PIPCP:PC61BM, that exhibits very low electronic disorder (Urbach energy less than 27 meV), very high carrier mobilities in the blend (field-effect mobility for holes >10-2 cm2 V-1 s-1), and a very low driving energy for initial charge separation (50 meV). These characteristics should give excellent performance, and indeed, the VOC is high relative to the donor energy gap. However, we find the overall performance is limited by recombination, with formation of lower-lying triplet excitons on the donor accounting for 90% of the recombination. We find this is a bimolecular process that happens on time scales as short as 100 ps. Thus, although the absence of disorder and the associated high carrier mobility speeds up charge diffusion and extraction at the electrodes, which we measure as early as 1 ns, this also speeds up the recombination channel, giving overall a modest quantum yield of around 60%. We discuss strategies to remove the triplet exciton recombination channel.

AB - Donor-acceptor organic solar cells often show high quantum yields for charge collection, but relatively low open-circuit voltages (VOC) limit power conversion efficiencies to around 12%. We report here the behavior of a system, PIPCP:PC61BM, that exhibits very low electronic disorder (Urbach energy less than 27 meV), very high carrier mobilities in the blend (field-effect mobility for holes >10-2 cm2 V-1 s-1), and a very low driving energy for initial charge separation (50 meV). These characteristics should give excellent performance, and indeed, the VOC is high relative to the donor energy gap. However, we find the overall performance is limited by recombination, with formation of lower-lying triplet excitons on the donor accounting for 90% of the recombination. We find this is a bimolecular process that happens on time scales as short as 100 ps. Thus, although the absence of disorder and the associated high carrier mobility speeds up charge diffusion and extraction at the electrodes, which we measure as early as 1 ns, this also speeds up the recombination channel, giving overall a modest quantum yield of around 60%. We discuss strategies to remove the triplet exciton recombination channel.

UR - http://hdl.handle.net/10754/622740

UR - http://pubs.acs.org/doi/full/10.1021/acsnano.6b06211

UR - http://www.scopus.com/inward/record.url?scp=85008199646&partnerID=8YFLogxK

U2 - 10.1021/acsnano.6b06211

DO - 10.1021/acsnano.6b06211

M3 - Article

C2 - 27809478

SN - 1936-0851

VL - 10

SP - 10736

EP - 10744

JO - ACS Nano

JF - ACS Nano

IS - 12

ER -

Limits for Recombination in a Low Energy Loss Organic Heterojunction

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