Enhanced Short-Wavelength Absorption and Effective Exciton Dissociation in NC₇₀BA-Based Ternary Polymer Solar Cells

Abstract

A ternary heterojunction strategy was employed to improve the photovoltaic performance of polymer solar cells (PSCs) by harvesting more short-wavelength photons and more efficient exciton dissociation. Ternary PSCs were fabricated by employing the wide-band-gap polymer PBDB-T-2F as the donor, the narrow-band-gap nonfullerene small-molecule IT-4F as the acceptor, and the fullerene derivative NC70BA as the third component to tune the light absorption, enlarge the energy band gap, and improve the charge-carrier dynamics of the ternary photoactive layer. The highest power conversion efficiency (PCE) of 13.90% is achieved in an optimized PBDB-T-2F:IT-4F:NC70BA ratio of 1:1.2:0.25. The introduction of NC70BA has complementary light absorption in the short-wavelength region (from 300 to 450 nm) and optimizes the exciton dissociation. The lowest unoccupied molecular orbital (LUMO) energy level of NC70BA is higher than that of IT-4F, which enlarges the energy band gap and enhances the open-circuit voltage (V OC). A very promising ternary heterojunction strategy with NC70BA as the third component is to develop highly efficient ternary PSCs.

Solution-Processed Self-Powered Panchromatic Organic Photodiode and Its Application in Biomedical Devices

“…Though the increment in thickness of the active layer can reduce the value of J d significantly, a trade-off exists between J ph and J d , when the active layer thickness is increased beyond a certain limit. The high P c values under short-circuit condition for all three devices indicate efficient exciton dissociation and charge collection without the assistance of external reverse bias. ,, It further suggests that the photodiodes can be utilized for panchromatic photodetection in a self-powered mode.…”

“…The high P c values under short-circuit condition for all three devices indicate efficient exciton dissociation and charge collection without the assistance of external reverse bias. 18,26,27 It further suggests that the photodiodes can be utilized for panchromatic photodetection in a self-powered mode.…”

Synthesis of D‐A copolymers based on thiadiazole and thiazolothiazole acceptor units and their applications in ternary polymer solar cells

“…Similar results have been observed for the active ternary layer based on P122 . These results indicate that a more effective exciton dissociation occurred in the ternary film than in the binary films 69–71 . The thin film PL spectra of pristine PC 71 BM and Y6 (excitation wavelength = 500 nm) is shown in Figure S15b and showed a strong absorption peak at 706 and 904 nm, respectively.…”

“…These results indicate that a more effective exciton dissociation occurred in the ternary film than in the binary films. [69][70][71] The thin film PL spectra of pristine PC 71 BM and Y6 (excitation wavelength = 500 nm) is shown in Figure S15b and showed a strong absorption peak at 706 and 904 nm, respectively. The PL spectra of PC 71 BM:Y6 (0.2:1.0) film showed a strong peak at 882 nm, which is significantly blue-shifted compared to pristine Y6, and the PL peak corresponding to the PC 71 BM is strongly quenched.…”

Perovskite and Polymeric Solar Cells: A Comparison of Advances and Key Challenges

“…Thus, for example, excitons can be dissociated in cells with two donors on the D1/A or D2/A interface. [ 11,103–105 ]…”