Surface Energy Induced Vertical Phase Separation of Nanomorphology in Polymer Solar Cells

Abstract

Efficient charge transport in inverted-structure polymer solar cells (i-PCSs) requires surface localization of the donor polymer in the bulk heterojunction (BHJ) film. For high-efficiency i-PCSs, vertical phase separation was induced between the PTB7 donor and PC71BM acceptor by attachment of a polymethylsulfoxide (PDMS) film on top of the BHJ film. The similar surface energies (SE) of the PDMS film attached to the as-spun active layer and the PTB7 molecules caused PTB7 to flow toward PDMS. Mixing tetrahydrofuran (THF) with PDMS further lowered the SE, reducing the difference between that of PDMS and PTB7 to less than 0.11 mN m −1. THF-treated PDMS efficiently attracted the PTB7 molecules, making BHJ active layer nanostructure amenable to charge transport and collection in the i-PSC. The maximum power conversion efficiency (PCE) of the i-PSCs increased from 6.93 to 8.14 % with respective 8.6 and 6.7 % enhancements of the short-circuit current density (J sc) and fill factor (FF).

Miscibility-Controlled Mechanical and Photovoltaic Properties in Double-Cable Conjugated Polymer/Insulating Polymer Composites

“…While in the JP02-PDMS system, the fibrous structures disappeared gradually at the blending content >10% (Figure f–h), simultaneous with greatly decreased RMS values from 2.58 nm to 0.788 nm, 0.649 nm, and 0.978 nm for the JP02-PDMS 10%, JP02-PDMS 15%, and JP02-PDMS 20% (Figure b–d), respectively. These changes may be attributed to the vertical phase separation caused by the immiscible compositing between JP02 and PDMS. ,, These changes would significantly influence the charge transporting properties of the films and the corresponding photovoltaic devices. Meanwhile, the fibrous microstructures had almost no change with increased bending ratios from 10 to 20% in the JP02-SBS and JP02-PS composite systems (Figure n–p and v–x), even though accompanied by enhanced rough surfaces (Figure j–l and r–t).…”

“…These changes may be attributed to the vertical phase separation caused by the immiscible compositing between JP02 and PDMS. 31,48,49 These changes would significantly influence the charge transporting properties of the films and the corresponding photovoltaic devices. Meanwhile, the fibrous microstructures had almost no change with increased bending ratios from 10 to 20% in the JP02-SBS and JP02-PS composite systems (Figure 4n−p and 4v−x), even though accompanied by enhanced rough surfaces (Figure 4j−l and 4r−t).…”

Low-cost Millimeter Scale Single-Layer MoS2 Synthesis via Chemical Vapor Deposition

“…It has also the potential for low-cost 2D-MoS 2 fabrication with uniform layer thickness over macroscopic size scales, making it a preferred method for future technology integration [4]. In the earlier works, MoS 2 lms or monolayers have been synthesized via the CVD method [1,3,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. In these studies, high growth temperatures and gas ow rates, usage of ammable gases such as H 2 , low pressures, usage of high amounts of precursor powders, and the synthesis of small surface area monolayers make it essential to carry out new studies.…”

Optical Properties of EVA Films Including V570 for Transparent Luminescent Solar Concentrator

“…A luminescent solar concentrator (LSC) using luminescent molecules and a polymer matrix is a device for selective absorption of sunlight and for collecting the emitted light to the side edges of the collector through total internal reflection (TIR) [1 4]. An LSC reduces the amount of solar cells required for solar power generation [5,6], and can selectively utilize the desired light in the solar spectrum according to the luminophore used. It is also possible to fabricate transparent photovoltaic devices by engineering the concentration of luminophores in LSC films.…”