Phenoxy Group-Containing Asymmetric Non-Fullerene Acceptors Achieved Higher VOC over 1.0 V through Alkoxy Side-Chain Engineering for Organic Solar Cells

Chuan-Hsin Wang; Manohar Reddy Busireddy; Sheng-Ci Huang; Hebing Nie; Yu-Shuo Liu; Bing-Yong Lai; Ling-Huan Meng; Wei-Tsung Chuang; Markus C Scharber; Jiun-Tai Chen; Chain-Shu Hsu

doi:10.1021/acsami.3c13833

Phenoxy Group-Containing Asymmetric Non-Fullerene Acceptors Achieved Higher V_OC over 1.0 V through Alkoxy Side-Chain Engineering for Organic Solar Cells

ACS Appl Mater Interfaces. 2023 Dec 20;15(50):58683-58692. doi: 10.1021/acsami.3c13833. Epub 2023 Dec 10.

Authors

Chuan-Hsin Wang^{1

2}, Manohar Reddy Busireddy^{1

2}, Sheng-Ci Huang^{1

2}, Hebing Nie^{1

2}, Yu-Shuo Liu^{1

2}, Bing-Yong Lai^{1

2}, Ling-Huan Meng^{1

2}, Wei-Tsung Chuang³, Markus C Scharber⁴, Jiun-Tai Chen^{1

2}, Chain-Shu Hsu^{1

2}

Affiliations

¹ Department of Applied Chemistry, National Yang Ming Chiao Tung University, 1001 University Rood, Hsinchu 300093, Taiwan.
² Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, 1001 University Rood, Hsinchu 300093, Taiwan.
³ National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu 30073, Taiwan.
⁴ Linz Institute of Organic Solar Cells (LIOS), Institute of Physical Chemistry, Johannes Kepler University Linz, Altenbergerstrasse 69, Linz 4040, Austria.

PMID: 38073043
DOI: 10.1021/acsami.3c13833

Abstract

Alkoxy side chain engineering on the β-position of the thienothiophene units of Y6 derivatives plays a vital role in improving photovoltaic performances with simultaneously increasing open-circuit voltage (V_oc) and fill factor (FF). In this work, we prepared a series of asymmetric non-fullerene acceptors (NFAs) by introducing alkoxy side chains and phenoxy groups on the state-of-the-art Y6-derivative BTP-BO-4F. For the comparison, 2O-BO-4F with a symmetric alkoxy side chain on the outer thiophene units and BTP-PBO-4F with an asymmetric N-attached phenoxy alkyl chain on the pyrrole ring are synthesized from BTP-BO-4F. Thereafter, we construct four asymmetric NFAs by introducing different lengths of linear/branched alkoxy chains on the β-position of the thienothiophene units of BTP-PBO-4F. The resulting NFAs, named L10-PBO, L12-PBO, B12-PBO, and B16-PBO (L = linear and B = branched alkoxy side chains), are collectively called OR-PBO-series. Unexpectedly, all OR-PBO NFAs exhibit strong edge-on molecular packing and weaker π-π interactions in the film state, which diminish the charge transfer in organic solar cell (OSC) devices. As a consequence, the optimal devices of OR-PBO-based binary blends show poor photovoltaic performances [power conversion efficiency (PCE) = 6.52-9.62%] in comparison with 2O-BO-4F (PCE = 12.42%) and BTP-PBO-4F (PCE = 15.30%) reference blends. Nevertheless, the OR-PBO-based binary devices show a higher V_oc and smaller V_loss. Especially, B12-PBO- and B16-PBO-based devices achieve V_oc over 1.00 V, which is the highest value of Y-series OSC devices to the best of our knowledge. Therefore, by utilizing higher V_oc of OR-PBO binary blends, B12-PBO and B16-PBO are incorporated into the PM6:BTP-PBO-4F-based binary blend and fabricated ternary devices. As a result, the PM6:BTP-PBO-4F:B12-PBO ternary device delivers the best PCE of 15.60% with an increasing V_oc and FF concurrently.

Keywords: alkoxy side-chain engineering; asymmetric NFAs; high open-circuit voltage; low voltage loss; o-xylene; ternary devices.