P3HT-Based Organic Solar Cells with a Photoresponse to 1000 nm Enabled by Narrow Band Gap Nonfullerene Acceptors with High HOMO Levels

Abstract

Three narrow band gap (NBG) acceptors, namely, TTDTC-0F, TTDTC-2F, and TTDTC-4F, were synthesized by introducing a strong electrondonating unit as the central core. The enhanced intramolecular charge transfer endows the three acceptors with high-lying highest occupied molecular orbitals (HOMOs) of ∼−5.20 eV and ultranarrow band gaps (∼1.25 eV). When blended with poly(3hexylthiophene) (P3HT), all organic solar cells (OSCs) exhibited a broad photoresponse from 300 to ∼1000 nm. Among them, P3HT:TTDTC-4F-based devices achieved the highest efficiency of 7.81% with a prominent J sc exceeding 22 mA•cm −2 . This study demonstrates that the conjugated molecules with high HOMOs can also function as acceptor materials for P3HT-based OSCs, which opens a window to increase PCEs of P3HT-based OSCs in the future to the level of the devices based on the current state-of-the-art polymer donor materials.

Machine learning assisted identification of the matched energy level of materials for high open circuit voltage in binary organic solar cells

“…The high LUMO (A) allows the rapid electron transfer from D, and the elevated HOMO (A) is conducive for achieving the narrow optical bandgap for broadening the absorption spectrum of A, which can offer effective charge transport. 38 Previous studies have also demonstrated that V oc can be effectively enhanced by designing D with deeper-lying HOMO levels or A with higher-lying LUMO levels, 39 which is consistent with the analysis results of our prediction model. For the work function of the hole transport layer (WF-HTL) and work function of the electron transport layer (WF-ETL), most points are concentrated at the SHAP value of 0, which means that these two features are not important factors for V oc .…”

Recent progress in non-fused ring electron acceptors for high performance organic solar cells

“…In order to broaden the absorption range, Li et al designed a narrow band gap NFREA TTDTC-4F by introducing a strong electron-donating thieno[3,2- b ]thiophene (TT) unit as the central core. 44 TTDTC-4F possessed a narrow bandgap of 1.25 eV with an absorption edge around 1000 nm. After device optimization, the P3HT:TTDTC-4F based device achieved a PCE of 7.81% with a higher J sc of 22.5 mA cm −2 .…”

A narrow band gap non-fullerene electron acceptor based on a dithieno-3,2-b:2′,3′-dlpyrrole unit for high performance organic solar cells with minimal highest occupied molecular orbital offset

“…[22][23][24][25][26][27] Among these material design strategies, designing A-D-A type NFSMAs with a narrow band gap is an effective strategy to extend the absorption spectrum and increase the short circuitcurrent (J sc ), and thus improve the PCEs of OSCs based on A-D-A type NFSMAs. [28][29][30][31][32][33] In general, enhancing the electrondonating ability of the donor fused-ring core of the A-D-A type NFSMAs can improve the enhanced intramolecular-charge transfer (ICT) effect, and thereby reduce the band gap of the A-D-A type NFSMAs. For example, Bazan and coworkers designed a new NFSMAs IOTIC-2F by introducing a strong electron-donating group in the donor core of NFSMAs.…”