Nonhalogenated Solution‐Processed Donor‐Dispersed Planar Heterojunction Organic Solar Cells with Enhanced Homogeneity in Vertical Phase Separation

Abstract

Realization of state‐of‐the art efficiencies in organic photovoltaics (OPV) generally relies on using toxic halogenated solution processing to arrive at the desired nanomorphology and optoelectronic responses, whereas the photovoltaic performance in nonhalogenated solution (NHS)‐based OPVs is yet nonsatisfactory, mainly related to the difficulty of morphological control. Herein, a conceptual approach of donor‐dispersed planar heterojunction (DD‐PHJ) for improving the regulation of phase morphology and photovoltaic behaviors in NHS‐processed OPVs is proposed, afforded by dispersing an ordered liquid crystal guest donor BTR‐Cl into the nonfullerene acceptor host with sequential film deposition. The combined investigation shows that the inclusion of BTR‐Cl plays a regulatory role in enhancing the crystallization, intermolecular donor/acceptor miscibility, and homogeneity in the donor–acceptor phase separation along vertical direction, which is conducive to improved charge transfer and reduced photovoltage loss. Of importance, the described DD‐PHJ approach is applicable to representative OPV material systems, leading to a champion efficiency of 18.21% in devices prepared with NHS. This work provides a promising prospect toward high‐efficiency and green solution‐processed OPV devices.

A high-efficiency and stable organic solar cell with balanced crystallization kinetics

“…This particularity can contribute to the reduction of bimolecular charge recombination, thus helpful for the improvement of the photocurrent and device fill factor. 46 On top of this, more pronounced enrichment of the acceptor host in the quaternary blend film is indicated (Fig. 3(d)), providing benefits for the suppression on interfacial charge accumulation and recombination.…”

Advances in layer-by-layer processing for efficient and reliable organic solar cells

“…Li et al proposed regulating the film morphology in LBL OSCs by diffusing a liquid crystalline BTR-Cl as the molecular donor into the fullerene-free host using non-halogenenated solvent o -XY. 157 The inclusion of BTR-Cl enhanced the crystallization leading to homogeneous D–A phase separation along the vertical direction, thus improving the charge transfer and lowering the voltage loss, thus achieving an impressive PCE of 18.21% for D18-Cl/BTP-eC9:BTR-Cl ternary OSCs. The device based on PM6/Y7-BO:BTR-Cl achieved a PCE of 17.15%.…”

High-efficiency flexible organic solar cells with a polymer-incorporated pseudo-planar heterojunction

“…The pseudo-planar heterojunction (PPHJ), obtained by sequential-casting (SC) with the separately dissolved donor and acceptor materials, can effectively address these challenges [ 11 – 13 ]. Nevertheless, the active layer based on PPHJ often exhibit an undesirable vertical component distribution and insufficient D/A interfaces, leading to low current density and poor photovoltaic performance [ 14 ]. This issue is exacerbated in the non-halogenated solvent-processed PPHJ OSCs due to the poor solubility of organic materials in non-halogenated solvents and significant solubility difference between the polymer donor and small molecule acceptor [ 15 ].…”