Understanding the effect of N2200 on performance of J71: ITIC bulk heterojunction in ternary non-fullerene solar cells

Abstract

None-fullerene solar cells with ternary architecture have attracted much attention because it is an effective approach for boosting the device power conversion efficiency.Here, the crystalline polymer N2200 as the third component is integrated into J71:ITIC bulk heterojunction. A series of characterizations indicate that N2200 could increase photo-harvesting, balanced hole and electron mobilities, enhanced exciton dissociation, and suppressed charge recombination, which result in the comprehensive improvement of open circuit voltage, short circuit current and fill factor in the device. Moreover, after introduction of N2200, the morphology of the ternary active layer is optimized, and the film crystallinity is improved. This work demonstrates that adding a small quantity of high crystallization acceptor into non-fullerene donor: acceptor mixture is a promising strategy toward developing high-performance organic solar cells.

Enhanced and Balanced Charge Transport Boosting Ternary Solar Cells Over 17% Efficiency

“…The electron affinity (EA) is obtained from the IP subtracting the optical absorption gap. [36] From the energy level diagrams illustrated in Figure 1c, the IP values of PM6, DRTB-T-C4, and Y6 are 5.22, 5.70, and 5.71 eV, respectively, and the EA values for 3.33, 3.72, and 4.34 eV, offering the quasi cascade-type energy levels at the ternary heterojunction interfaces. We use the ICT model and the so-called pinning energies, E ICT+ and E ICT− to predict ground state charge transfer at the heterojunctions, and the size and direction of the potential gradients so formed.…”

“…The surface energies of the different components are the main driving force for vertical phase separation in the blends, which can be estimated from their contact angles. [36,47] We measure the contact angles of PM6, DRTB-T-C4, and Y6 using water and ethylene glycol shown in Figure S11 in the Supporting Information, and the parameters of surface energy are displayed in Table S3 in the Supporting Information. The corresponding surface energies are calculated to be 16.1, 20.6, and 24.8 mJ m −2 , respectively, suggesting that PM6 with the smallest surface energy is likely to segregate to the top film/air, while Y6 with the largest surface energy is likely to concentrate on the substrate/ film.…”

A Fully Non‐fused Ring Acceptor with Planar Backbone and Near‐IR Absorption for High Performance Polymer Solar Cells

“…As shown in the Supporting Information, Figure S4, the IP values of the o ‐4TBC‐2F films before and after thermal annealing were calculated to be −5.54 and −5.58 eV, respectively. Furthermore, the electron affinity (EA) values of the as‐cast and annealed o ‐4TBC‐2F films were −4.07 and −4.24 eV, respectively, which were obtained by subtracting the IP from E g opt [15] . Hence, the dramatic decrease in the V oc of o ‐4TBC‐2F‐based devices after thermal annealing can be ascribed to a decrease in the optical band gap and the EA values, which was caused by a reorganization of the acceptor molecules in the blend films.…”

“…The J-V curves and photovoltaic parameters are shown in Figure 3a and Table 2, As shown in the Supporting Information, Figure S4, the IP values of the o-4TBC-2F films before and after thermal annealing were calculated to be À5.54 and À5.58 eV,r espectively.F urthermore,t he electron affinity (EA) values of the as-cast and annealed o-4TBC-2F films were À4.07 and À4.24 eV,respectively,which were obtained by subtracting the IP from E g opt . [15] Hence,the dramatic decrease in the V oc of o-4TBC-2F-based devices after thermal annealing can be ascribed to adecrease in the optical band gap and the EA values,which was caused by ar eorganization of the acceptor molecules in the blend films.A sd etermined by UV/Vis absorption and grazingincidence wide-angle X-ray scattering (GIWAXS) measurements (see below), the acceptor molecules had closer intermolecular p-p stacking after thermal annealing at 100 8 8Cfor 5min. Unlike o-4TBC-2F,the photovoltaic performance of the m-4TBC-2F-based devices was slightly reduced after thermal annealing (Supporting Information, Table S4).…”

Non-halogenated and non-volatile solid additive for improving the efficiency and stability of organic solar cells

“…Given that exciton separation is critical in the photovoltaic processes of OSCs, a subtle change in the nano-morphology of the photoactive layer may have a signicant impact on charge dynamics during device operation. [57][58][59][60] Therefore, time-resolved photoluminescence (TRPL) measurements were performed on fresh and thermally aged lms with and without additives to investigate the charge-transfer dynamics in their photoactive layers. The TRPL spectra and corresponding decay lifetimes of PM6, Y6, and their blend lms are presented in Fig.…”