Near-infrared absorbing acceptor with suppressed triplet exciton generation enabling high performance tandem organic solar cells

Abstract

Reducing the energy loss of sub-cells is critical for high performance tandem organic solar cells, while it is limited by the severe non-radiative voltage loss via the formation of non-emissive triplet excitons. Herein, we develop an ultra-narrow bandgap acceptor BTPSeV-4F through replacement of terminal thiophene by selenophene in the central fused ring of BTPSV-4F, for constructing efficient tandem organic solar cells. The selenophene substitution further decrease the optical bandgap of BTPSV-4F to 1.17 eV and suppress the formation of triplet exciton in the BTPSV-4F-based devices. The organic solar cells with BTPSeV-4F as acceptor demonstrate a higher power conversion efficiency of 14.2% with a record high short-circuit current density of 30.1 mA cm−2 and low energy loss of 0.55 eV benefitted from the low non-radiative energy loss due to the suppression of triplet exciton formation. We also develop a high-performance medium bandgap acceptor O1-Br for front cells. By integrating the PM6:O1-Br based front cells with the PTB7-Th:BTPSeV-4F based rear cells, the tandem organic solar cell demonstrates a power conversion efficiency of 19%. The results indicate that the suppression of triplet excitons formation in the near-infrared-absorbing acceptor by molecular design is an effective way to improve the photovoltaic performance of the tandem organic solar cells.

Frontier Molecular Orbital Offset as an Empirical Descriptor for Predicting Short Circuit Current of Nonfullerene Organic Solar Cells

“…To evaluate the generalization ability of the XGBoost model on unseen data, three types of high-performance OSCs (measured J sc value >27 mA cm À2 ) with different binary active layers (e.g., PBDB-T/BTP-Se, PTB7-Th/BTPSV-4F, and PTB7-Th/BTPSeV-4F) were used for verifying the prediction results. [48,49] The relative error between the measured J sc and the predicted J sc is in Table 1. Most importantly, the relative errors for PBDB-T/BTP-Se, PTB7-Th/BTPSV-4F, and PTB7-Th/BTPSeV-4F were estimated to be 13.2%, 14.2%, and 16.1%, respectively.…”

Theoretical investigation on the functional group modulation of UV-Vis absorption profiles of triphenylamine derivatives

“…[1][2][3][4][5] For the vast majority of optoelectronic devices in which a myriad of photophysical and photochemical processes occur, light absorption is one of the most premier processes that start a succession of workflow. [6][7][8] The response of OSMs towards sunlight, which can be directly observed using UV-Vis absorption spectroscopy and other optical techniques, significantly affects the photoelectric performance of OSMbased devices.…”

Design and screening of B–N functionalized non-fullerene acceptors for organic solar cells via multiscale computation

“…They observed that polymer PCPDT functionalized with B-N system showed an improved V OC and PCE, lower HOMO/LUMO levels with a narrower optical bandgap as compared to bare PCPDT polymer. 27 Despite these merits of B-containing p-cores, the development of novel NFAs exhibiting wider absorption in the near-infrared region, 28 and n-type charge transport 25 is a key challenge for further improvement of PCEs in organic solar cells.…”