The synthesis and photovoltaic properties of A–D–A-type small molecules containing diketopyrrolopyrrole terminal units

Abstract

A series of novel A-D-A structured small molecule photovoltaic (PV) materials [CZ(TDPP) 2 , DPA(TDPP) 2 , PTZ(TDPP) 2 and FL(TDPP) 2 ] with diketopyrrolopyrrole (DPP) as an electron-withdrawing group were synthesized and characterized. These small molecular donors exhibit excellent solubility in common organic solvents. The density functional theory (DFT) calculations demonstrated the intramolecular charge transfer (ICT) behavior of the synthesized PV materials and an efficient charge separation was observed by a fluorescence quenching experiment. In addition, their photophysical and electrochemical properties show that they harvest sunlight over the entire visible spectrum range and keep appropriate energy levels to satisfy the requirement of solution-processable OSCs. Therefore, we explored the PV properties of the synthesized donors by fabricating BHJ solar cells with a typical structure of ITO/PEDOT:PSS/Donors:PC 61 BM/LiF/Al. Among them, CZ(TDPP) 2 revealed a promising performance in PV devices with a power conversion efficiency (PCE) of 1.50%, along with an open-circuit voltage (V OC ) of 0.66 V, a short-circuit current density (J SC ) of 4.12 mA cm À2 , and a fill factor (FF) of 0.44, under an illumination of AM 1.5G (80 mW cm À2 ).

Study on the Controlled Gel Formation and Photochromic Properties of a New Cholesterol-bridge-naphthopyran Dyad

“…17,21 Therefore, the free volume around the NP-MCB molecules and the mobility of the bond rotating were reduced, and then the photochromic performance of NP-MCB was slowed down. 31 The maximum absorption peaks of NP-MCB in solution and S gel were at 486 nm and 499 nm, respectively. The red-shift of absorbance band of open-form NP-MCB also should be attributed to the closely molecular aggregation in gel state.…”

Structure–property relationships for bis-diketopyrrolopyrrole molecules in organic photovoltaics

“…Thermal annealing (110 °C, 10 min.) improved the TT-S: [60]PCBM cells by about 25%, but resulted in a 50% or more loss in performance for the DTT-S: [60]PCBM and BDT-S: [60]PCBM cells.…”

“…Organic solar cells were fabricated by sandwiching a bulk heterojunction of the bis-DPP molecules and [60]PCBM between a transparent ITO/PEDOT:PSS front electrode and a LiF/Al back electrode on glass substrates. The active layer was deposited via spin coating from chloroform with and without co-solvents.…”

“…1, there are three different electron-rich aromatic cores TT, DTT, and BDT. Solar cells of these molecules blended with [60]PCBM were optimized for co-solvent and thermal annealing. Adding 0.2% 1chloronapthalene (1-CN) as co-solvent in chloroform, gave better performance than using o-dichlorobenzene (o-DCB) or 1,8-diiodooctane (DIO) for all three blends.…”

An efficient photovoltaic device based on novel D–A–D solution-processable small molecules

“…It is thus speculated that the combination of excellent optoelectronic properties of 3, 6-carbazole unit and the merits of donor-acceptor molecular design would produce some promising donor materials for organic solar cell. Despite these promising aspects, only few organic small molecules based on 3-carbazole have been studied so far for photovoltaic applications [31,32].…”