Aqueous Soluble Fullerene Acceptors for Efficient Eco-Friendly Polymer Solar Cells Processed from Benign Ethanol/Water Mixtures

Abstract

We present a new series of fullerene derivatives that exhibit solubility in ethanol/water solvent mixtures and implement these materials to fabricate polymer solar cells (PSCs) using environmentally benign solvents. In order to simultaneously optimize the processability of the fullerenes in ethanol/water solvent mixtures and device performance, different fullerene mono-adducts were designed by introducing oligoethylene glycol side chains with different lengths and number of branches. As a result, we achieved power conversion efficiencies up to 1.4% for PSCs processed from benign ethanol/water mixtures in air. Significantly, the new alcohol/water-soluble fullerene derivatives displayed electron mobilities up to 1.30 × 10 −4 cm 2 V −1 s −1 , 150 times higher than those of a previously reported alcohol-soluble fullerene bis-adduct, owing to efficient packing of the fullerenes. Femtosecond transient absorption spectroscopy revealed the acceptor side chain to markedly impact geminate and/or nongeminate charge recombination in the PSCs. In addition, side chain optimization of these fullerenes produced well-intermixed morphologies with high domain purity when blended with p-type polymer to provide hole and electron transport pathways. Our results provide important guidelines for the design of electroactive materials for safe and environmentally benign fabrication of PSCs and other organic electronic devices.

Efficient and Air‐Stable Aqueous‐Processed Organic Solar Cells and Transistors: Impact of Water Addition on Processability and Thin‐Film Morphologies of Electroactive Materials

“…The PPDT2FBT‐A polymer donor was prepared by following the reported procedures, and the number‐average molecular weight and dispersity ( Đ ) of PPDT2FBT‐A were determined to be 20.5 kg mol −1 and 2.51, respectively, by size exclusion chromatography (SEC) calibrated with polystyrene standards. The PC 61 BO 12 fullerene monoadduct was synthesized by following the reported literature procedure …”

“…Materials : PPDT2FBT‐A and PC 61 BO 12 were synthesized according to the previous literature . Detailed procedures for the synthesis of the other OEG‐based polymers, poly[(4,8‐bis(1,3‐bis(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)propan‐2‐yloxy)benzo[1,2‐b:4,5‐b′]dithiophene)‐alt‐(benzo[c] [1,2,5]thiadiazole)] (PBDTBT‐A) and poly[(2,5‐bis(1,3‐bis(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)propan‐2‐yloxy)benzene)‐alt‐(1,4‐bis(thiophen‐2‐yl)‐2,5‐difluorobenzene) (PPDT2FP‐A), were described in the Supporting Information.…”

Synthesis and Nonlinear Optical Studies on Organic Compounds in Laser-Deposited Films

“…Thin films of 2, prepared by spin coating of a CHCl 3 solution, highlight the ambipolar semiconducting behavior and also very good electron-transporting properties for fullerene 2 [92]. Kim et al synthesized new fullerene 3 soluble in ethanol/water solvent mixtures and implemented these materials to fabricate polymer solar cells (PSCs) using environmentally friendly solvents [93]. The results of this paper provide important guidelines for the design of aqueouselectroactive materials having high carrier mobilities suitable to achieve very efficient eco-PSCs.…”

Aggregation Controlled Charge Generation in Fullerene Based Bulk Heterojunction Polymer Solar Cells: Effect of Additive

“…Organic semiconductors (OSCs) have been intensively studied due to their unique electronic and optical properties. Their properties—including relatively easy and inexpensive fabrication, light weight, mechanical flexibility and compatibility with stretchability, and potential for non-toxic processing methods—open broad prospects for their applications in a variety of industrial and technological areas, including solar cells [ 1 , 2 ]. Considerable efforts have been dedicated to the development of polymer solar cells (PSCs) due to several advantages, such as high absorption coefficients [ 3 ], highly tunable molecular energy levels [ 4 ], and low reorganization energy associated with low voltage loss [ 5 , 6 ].…”