Conjugated polymers with controllable interfacial order and energetics enable tunable heterojunctions in organic and colloidal quantum dot photovoltaics

Yufei Zhong, Ahmad R. Kirmani, Xinzheng Lan, Joshua Carpenter, Annabel Rong-Hui Chew, Omar Awartani, Liyang Yu, Muhammad Rizwan Niazi, Oleksandr Voznyy, Hanlin Hu, Guy Olivier Ngongang Ndjawa, Max Lutz Tietze, Alberto Salleo, Harald Ade, Edward H. Sargent, Aram Amassian

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Conjugated polymers are widely used as photoactive and transport layers in organic and hybrid photovoltaics (PV), where the energetics of polymers are a key design criterion. Here, we show that significant variations in terminal molecular ordering between top and bottom surfaces of a wide range of conjugated polymer films can result in sizable interfacial ionization energy (IE) differences by as much as 0.33 eV, which has significant impact on organic and hybrid PV devices. Such tunability is surprisingly seen even in nominally amorphous polymers. We devise a strategy leveraging wet and dry laminations to form donor–acceptor planar heterojunction (PHJ) devices using exposed and buried surfaces of donor polymers and demonstrate meaningful influence over the open circuit voltage (V$_OC$) by up to 0.32 V. We use this insight to devise a controlled intermixing approach which yields superior V$_OC$ and J$_SC$ to conventional bulk heterojunction devices by leveraging the disordered interface to maximize V$_OC$ and the greater aggregation of the donor to increase the J$_SC$. We go on to demonstrate how judicious control of polymer surface IE benefits charge extraction in colloidal quantum dot PV devices in the role of hole transport layers. Our results show that polymer interfacial and bulk properties are both critical to the functionality of optoelectronic devices and should both be given prime consideration when designing heterojunction devices.
Original languageEnglish (US)
Pages (from-to)1788-1801
Number of pages14
JournalJournal of Materials Chemistry A
Issue number4
StatePublished - 2022

Bibliographical note

KAUST Repository Item: Exported on 2022-12-13
Acknowledgements: Y. Zhong acknowledges funding supported by Zhejiang Provincial Natural Science Foundation of China under grant no Y22E021579. H. Ade, J. Carpenter and O. Awartani acknowledge funding supported under ONR N000141512322 and N000141712204.


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