Fullerene-free polymer solar cells enabled with a PhI-based wide band gap donor polymer: promoting efficiencies via acceptor screening and device engineering. Issue 27 (27th June 2019)

• Record Type: Journal Article
• Authors: Meng, Huifeng; Li, Yongchun; Pang, Bo; Li, Yuqing; Zhan, Chuanlang; Huang, Jianhua
• Is Part Of: Journal of materials chemistry. Volume 7:Issue 27(2019)
• Page Start: 8442
• Page End: 8449
• Publication Date: 2019-06-27
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c9tc01932d
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Using a wide band gap polymer based on PhI, the enhanced efficiency of 10.17% was obtained by judicious acceptor screening and device optimization. Abstract : The development of a wide bandgap polymer for the preparation of high-performance fullerene-free polymer solar cells (PSCs) has been a hot topic. PBDT-PhI is a typical wide band gap polymer, which has been initially reported in our previous study ( Polym. Chem., 2013, 4, 2174) and recently applied in fullerene-free PSCs, affording the efficiency of 8.31% ( Macromolecules, 2017, 50, 8928). In this study, by judiciously selecting acceptors and systematic device optimizations, we promoted the efficiencies of PBDT-PhI-based fullerene-free PSCs beyond 10% for the first time. We first selected a series of commercial acceptors, e.g., IT-4F, ITIC, ITCT, and IEICO-4F, to match PBDT-PhI. Good complementary absorption was observed between PBDT-PhI and the four acceptors. Ultraviolet photoelectron spectroscopy (UPS) tests revealed suitable energy level alignments between PBDT-PhI and the acceptors, except for IEICO-4F; primary device preparation was carried out using chloroform (CF) as the spin-coating solvent and 1, 8-diiodoocane (DIO) as the additive, and the efficiencies of 8.18%, 7.99%, 8.86%, and 3.90% for IT-4F, ITIC, ITCT, and IEICO-4F, respectively, were obtained. Based on PBDT-PhI/ITCT, further device optimizations were conducted using high-boiling point chlorobenzene (CB) and CB/CF mixed solvents to spin-coat the active layers, and the enhanced efficiencies of 9.17% and 10.17%, respectively, were obtained. The best performance of the PBDT-PhI/ITCT-based devices prepared using the CB/CF mix solvent was ascribed to the highest charge dissociation rates and the weakest recombination losses.