Improved Performance for Inverted Organic Photovoltaics via Spacer between Benzodithiophene and Benzothiazole in Polymers

Abstract

In this work, the effects of the spacer between benzo[1,2-b;3,4-b']dithiophene (BDT) and dialkoxybenzothiadiazole (ROBT) in polymers were investigated for applications in organic solar cells. Polymer PBDT-2T-ROBT has a bi-thiophene (2T) spacer between the BDT and ROBT units, while PBDT-ROBT is a direct copolymer of BDT and ROBT. The polymer/PC 70 BM solar cells using both polymers were fabricated and optimized via polymer/fullerene ratio, solvent, and solvent additives. The spacer has significantly improved solar cell performance from 1.28% (Voc =0.77 V, Jsc = 3.13 mA/cm 2 , FF = 53.11 %) to 5.11% (Voc =0.66 V, Jsc = 13.33 mA/cm 2 , FF = 58.12%). The x-ray diffraction (XRD) spectra show the PBDT-2T-ROBT/PC 70 BM blended film is semicrystalline while PBDT-ROBT/PC 70 BM film is amorphous. This indicates that the spacer facilitates polymer organization for higher carrier mobility in the film. The atomic force microscopy (AFM) topography and phase images show that PBDT-2T-ROBT/PC 70 BM films form fibrillar networks, while PBDT-ROBT/PC 70 BM films exhibit larger granular morphology. The photoinduced charge extraction by linearly increasing voltage (Photo-CELIV) measurements show thatPBDT-2T-ROBT/PC 70 BM has a mobility of 9.59×10 -5 cm 2 /Vs, which is higher than the mobility of 8.64×10 -5 cm 2 /Vs for PBDT-ROBT/PC 70 BM film.

Light and Thermally Induced Evolutional Charge Transport in CH3NH3PbI3 Perovskite Solar Cells

“…37 This also indicates that the recombination process is largely suppressed in perovskite solar cells. Subsequently, we derived the parameters associated with charge recombination from Figure 2d by using use eqs 4 and 5 38,39 = + τ γ ( )…”

Bridge control of photophysical properties in benzothiazole-phenoxazine emitters – from thermally activated delayed fluorescence to room temperature phosphorescence

“…Benzothiazole (BTaz) is used here as a small acceptor molecule, which has already shown great potential in other fields of organic electronics such as organic photovoltaics (OPVs), 29 organic field-effect transistors (OFETs), 30,31 and OLEDs. 32 This acceptor unit is combined with phenoxazine (PXZ), a strong donor moiety commonly used in the field of TADF as it tends to give rise to stable high-energy triplet states and it has a large dihedral angle with adjacent groups.…”

4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophen‐4‐one (CPDTO) homopolymer with side chains on every other CPDTO

“…The active layer was spin‐coated from the solutions at 800 rpm/s for 60 s. The device structure was ITO/ZnO/active layer/MoO 3 /Ag. The details of substrate preparation and MoO 3 /Ag deposition have been published earlier …”