Binary Organic Solar Cells with 19.2% Efficiency Enabled by Solid Additive

Abstract

Morphology optimization is critical for achieving high efficiency and stable bulk-heterojunction (BHJ) organic solar cells (OSCs). Herein, the use of 3,5-dichlorobromobenzene (DCBB) with high volatility and low cost to manipulate evolution of the BHJ morphology and improve the operability and photostability of OSCs is proposed. Systematic simulations reveal the charge distribution of DCBB and its non-covalent interaction with the active layer materials. The addition of DCBB can effectively tune the aggregation of PBQx-TF:eC9-2Cl during film formation, resulting in a favorable phase separation and a reinforced molecular packing. As a result, a power conversion efficiency of 19.2% (certified as 19.0% by the National Institute of Metrology) for DCBB-processed PBQx-TF:eC9-2Cl-based OSCs, which is the highest reported value for binary OSCs, is obtained. Importantly, the DCBB-processed devices exhibit superior photostability and have thus considerable application potential in the printing of large-area devices, demonstrating outstanding universality in various BHJ systems. The study provides a facile approach to control the BHJ morphology and enhances the photovoltaic performance of OSCs.

A-DA′D-A Type Acceptor with a Benzoselenadiazole A′-Unit Enables Efficient Organic Solar Cells

“…In addition, to clearly evaluate the difference in V oc between these OSCs, we further calculated the V loss of the devices. First, the bandgaps of blend films ( E g PV ) were determined from the dEQE/d E curves in Figure b where E is the photon energy transformed from wavelength. − The E g PV of PM6:Y6, PM6:L8-BO, and PM6:Se46 blends was calculated to be 1.412, 1.439, and 1.421 eV, and combining the E g PV and V oc of corresponding devices can yield the V loss of 0.567, 0.558, and 0.542 eV for the Y6, L8-BO, and Se46-based devices, respectively. These results indicate that the Se46-based devices have the smallest V loss compared to that of the Y6- and L8-BO-based devices; thus, the device based on Se46 with a lower bandgap can exhibit a higher V oc in comparison with the Y6- and L8-BO-based devices.…”

Morphology Controlling of All‐Small‐Molecule Organic Solar Cells: From Donor Material Design to Device Engineering

“…[ 5–7 ] As a result of material design innovation and devices engineering, the PCE of single‐junction OSCs has surpassed 19%. [ 8–12 ]…”

“…[5][6][7] As a result of material design innovation and devices engineering, the PCE of single-junction OSCs has surpassed 19%. [8][9][10][11][12] Solution-processed BHJ OSCs have emerged as the next generation of photovoltaic techniques owing to the low cost, easy fabrication, and flexibility. Significantly, OSCs possess translucent properties, making them ideally suited for building integrated photovoltaic and indoor applications.…”

Detrimental Effects of “Universal” Singlet Photocrosslinkers in Organic Photovoltaics

“…The power conversion efficiency (PCE) of organic photovoltaics (OPVs) has been dramatically improved to over 19% in the past few decades. − This is mainly due to the development of new organic semiconductors, including non-fullerene electron acceptors, which are suitable for photoinduced charge generation and charge transport. − The high performance is achieved by mixed bulk heterojunction (BHJ) films, in which the donor and acceptor molecules form interconnected material networks with a large interfacial area. The mixed morphology in the BHJ film has a large effect on the OPV performance and is sensitive to the film preparation and processing conditions; therefore, the OPV stability may depend on the morphology stability. , This effect is particularly pronounced in polymer/fullerene systems, where the long-term thermal annealing of the films results in extensive aggregation of the fullerene acceptors .…”