Recently Advanced Polymer Materials Containing Dithieno[3,2‐b:2′,3′‐d]phosphole Oxide for Efficient Charge Transfer in High‐Performance Solar Cells

Abstract

Two novel semiconducting polymers based on benzodithiophene and dithienophosphole oxide (DTP) units are designed and synthesized. A novel electron‐deficient DTP moiety is developed. Surprisingly, the introduction of DTP units brings highly polarizable characteristics, which is beneficial for the photocurrent in solar cells. Thus, the donor–acceptor type of conjugated polymers based on this novel acceptor has superior charge transfer properties and highly efficient PL quenching efficiencies. As a result, polymer solar cells (PSCs) with high power conversion efficiencies of 6.10% and 7.08% are obtained from poly(3,5‐didodecyl‐4‐phenylphospholo[3,2‐b:4,5‐b']dithiophene–4‐oxide‐alt‐4,8‐bis(5‐decylthiophen‐2‐yl)benzo[1,2‐b:4,5‐b']dithiophene) (PDTP–BDTT) and PDTP–4‐oxide‐alt‐4,8‐bis(5‐decylselenophen‐2‐yl)benzo[1,2‐b:4,5‐b']dithiophene) (PDTP–BDTSe), respectively, when the photoactive layer is processed with the 1,8‐octanedithiol (ODT) additive. The PDTP–BDTSe copolymer is now the best performing DTP‐based material for PSCs. Using the polarizable unit strategy determined in this study for the molecular design of conjugated polymers is expected to greatly advance the development of organic electronic devices.

Effect of Backbone Sequence of a Naphthalene Diimide-Based Copolymer on Performance in n-Type Organic Thin-Film Transistors

“…The more than 10 times higher electron mobility obtained for PNDI-VSV than PNDI-VTV OFETs can be explained by the well-known selenophene effect. Selenophene-based polymers can have stronger intermolecular attraction than thiophene-based analogues due to a larger dipole moment in selenophene than thiophene . However, the electron mobilities of both PNDI-VSV and PNDI-VTV OFETs are much lower than those of PNDI-TVT (1.5 cm 2 /(V·s)) and PNDI-SVS (2.4 cm 2 /(V·s)) OFETs.…”

“…Selenophene-based polymers can have stronger intermolecular attraction than thiophene-based analogues due to a larger dipole moment in selenophene than thiophene. 32 However, the electron mobilities of both PNDI-VSV and PNDI-VTV OFETs are much lower than those of PNDI-TVT (1.5 cm 2 /(V•s)) and PNDI-SVS (2.4 cm 2 /(V•s)) OFETs. The operational stability of PNDI-VTV and PNDI-VSV OFETs was investigated under constant bias conditions (V G and V D = 80 V).Figure 3f,g shows the change in normalized drain current (I D ), threshold voltage (ΔV th ), and onset voltage (ΔV on ) of PNDI-VTV and PNDI-VSV OFETs after constant bias for 4000 s. The PNDI-VTV OFETs showed poor operational stability with a large shift of normalized I D of ∼17% from its initial value, with ΔV th of 32 V and ΔV on of 8 V after the bias stress.…”

Effect of Energy Alignment, Electron Mobility, and Film Morphology of Perylene Diimide Based Polymers as Electron Transport Layer on the Performance of Perovskite Solar Cells

“…Figure d gives the energy level diagram of the PerSCs with different PX-PDI ETLs. The LUMO of PV-PDI, PT-PDI, PSe-PDI, PDBS-PDI, and PCPDT-PDI is −4.05, −3.94, −3.97, −3.71, and −3.84 eV, respectively. − Because the electron-donating groups tend to upshift LUMO level while the electron-withdrawing tend to down-shift LUMO level, PX-PDIs exhibit various LUMO levels because of the different electron-donating and electron-withdrawing nature of V, T, Se, DBS, and CPDT groups. The energy levels of CH 3 NH 3 PbI 3 , PEDOT:PSS, FTO, and Al are taken from the literature. , The LUMOs of PV-PDI, PT-PDI, and PSe-PDI are lower than that of CH 3 NH 3 PbI 3 (−3.90 eV), about 0.06–0.15 eV, which will facilitate the electron transfer from perovskite to ETLs.…”

Toward Efficient Polymer Solar Cells Processed by a Solution‐Processed Layer‐By‐Layer Approach

“…Two significant absorption peaks in the long wavelength region can be observed. The peak at 580 nm should be attributed to intramolecular π–π* transition along the conjugated backbones, while the shoulder peak at ≈620 nm should be attributed to the π–π* stacking of the backbones . When the temperature of the solution is increased from 10 to 110 °C, the shoulder peak is still very strong and the absorption onset does not blue‐shift, which indicates that PBDB‐TFS1 has strong aggregation effect under high temperature .…”