Title: Donor End‐Capped Alkyl Chain Length Dependent Non‐Radiative Energy Loss in All‐Small‐Molecule Organic Solar Cells

Abstract

Abstract A critical bottleneck for further efficiency breakthroughs in organic solar cells (OSCs) is to minimize the non‐radiative energy loss ( e Δ V _nr ) while maximizing the charge generation. With the development of highly emissive low‐bandgap non‐fullerene acceptors, the design of high‐performance donors becomes critical to enable the blend with the electroluminescence quantum efficiency to approach or surpass the pristine acceptor. Herein, by shortening the end‐capped alkyl chains of the small‐molecular donors from hexyl (MPhS‐C6) to ethyl (MPhS‐C2), the material obtained aggregation that was insensitive to thermal annealing (TA) along with condensed packing simultaneously. The former leads to small phase separation and suppressed upshifts of the highest occupied molecular orbital energy level during TA, and the latter facilitates its efficient charge‐transport at aggregation‐less packing. Hence, the Δ V _nr decreases from 0.242 to 0.182 V, from MPhS‐C6 to MPhS‐C2 based OSCs. An excellent PCE of 17.11% is obtained by 1,8‐diiodoctane addition due to almost unchanged high J _sc (26.6 mA cm ⁻² ) and V _oc (0.888 V) with improved fill factor, which is the record efficiency with the smallest energy loss (0.497 eV) and Δ V _nr (0.192 V) in all‐small‐molecule OSCs. These results emphasize the potential material design direction of obtaining concurrent TA‐insensitivemore » aggregation and condensed packing to maximize the device performances with a super low Δ V _nr .« less

Authors:

Zhang, Lili ^[1]; Sun, Rui ^[2]; Zhang, Ziqi ^[3]; Zhang, Jianqi ^[3]; Zhu, Qinglian ^[4]; Ma, Wei ^[4]; Min, Jie ^[2]; Wei, Zhixiang ^[3]; Deng, Dan  ^[3]

• Search DOE PAGES for author "Deng, Dan"
• Search DOE PAGES for ORCID "0000-0001-7938-6679"

---

+ Show Author Affiliations

1. CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology Beijing 100190 P. R. China, Sino‐Danish Center for Education and Research Sino‐Danish College University of Chinese Academy of Sciences Beijing 100049 P. R. China
2. The Institute for Advanced Studies Wuhan University Wuhan 430072 P. R. China
3. CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology Beijing 100190 P. R. China
4. State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 P. R. China

Publication Date:

Thu Nov 03 00:00:00 EDT 2022

Sponsoring Org.:

USDOE

OSTI Identifier:

1896940

Grant/Contract Number:  

DE‐AC02‐05CH11231

Resource Type:

Publisher's Accepted Manuscript

Journal Name:

Advanced Materials

Additional Journal Information:

Journal Name: Advanced Materials Journal Volume: 34 Journal Issue: 50; Journal ID: ISSN 0935-9648

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

Germany

Language:

English