Single Material Solar Cells: the Next Frontier for Organic Photovoltaics?

Abstract

An overview of various approaches for the realization of single‐material organic solar cells (SMOCs) is presented. Fullerene‐conjugated systems dyads, di‐block copolymers, and self‐organized donor‐acceptor molecules all represent different possible approaches towards SMOCs. Although each of them presents specific advantages and poses specific problems of design and synthesis, these different routes have witnessed significant progress in the past few years and SMOCs with efficiencies in the range of 1.50% have been realized. These performances are already higher than those of bi‐component bulk heterojunction solar cells some ten years ago, demonstrating that SMOCs can represent a credible approach towards efficient and simple organic solar cells. Possible directions for future research are discussed with the aim of stimulating further research on this exciting topic.

Mesogenic complementary absorbing dyads based on porphyrin and perylene units

“…These single-component photovoltaic materials possess multifunctions such as light harvesting, exciton dissociation and electron and hole transport. Moreover, several major advantages, such as a considerable simplification of device fabrication, stabilization of the morphology of the active material, and efficient (or fast) charge separation can be expected in the single-component OSCs [11]. At present, the PCE for single-component OSCs has surpassed 2% [12,15,17], which is lower than that of BHJ solar cells.…”

“…Recently [10], more than 13% PCE was obtained by blending a fluorinated p-conjugated polymer with a fluorinated fullerene-free small-molecule acceptor. In spite of these remarkable performances, the realization of solution-processed BHJ solar cells still poses a number of problems related to both the nature of the active materials and the fabrication process [11]. For example, the finecontrol of phase separation and achieving high chargecarrier mobility in active layers are still very difficult with BHJ solar cells [ As another interesting strategy, electron donoracceptor dyad, triad, multiad and block copolymer molecules or all-in-one molecules where the electron donor (D) and acceptor (A) units are covalently linked in a single molecule have been reported for their potential as photovoltaic materials [12,[14][15][16][17][18][19].…”

“…This is because the design of electron donor-acceptor molecules for efficient single-component OSCs is in fact difficult. Some important prerequisites for solar cell applications, such as strong and broad optical absorption, the energy level matching of the donor and acceptor units, the prevention of charge recombination and the efficient transport of the separated charges to the electrodes, need to be considered and balanced [11].…”

Separated crystallization of donor and acceptor in oligo(p-phenylenevinylene)-naphthalenediimide dyad films

“…Dyad molecules, in which the D and A moieties are covalently attached to each other, have been intensively studied for controlling the donor/acceptor (D/A) nanomorphology [14]. The efficiency has been improved from about 0.1% in early studies to more than 1% recently [15][16][17].…”

Solid State Physicochemical Properties and Applications of Organic and Metallo- Organic Fullerene Derivatives

“…In combination with electron-donating conjugated molecules, fullerene derivatives have been employed for charge-separation [182] and light-detection [183] applications that exploit their high electron affinity.…”