Single-Component Organic Solar Cells with Competitive Performance

Abstract

Organic semiconductors with chemically linked donor and acceptor units can realize charge carrier generation, dissociation and transport within one molecular architecture. These covalently bonded chemical structures enable single-component organic solar cells (SCOSCs) most recently to start showing specific advantages over binary or multi-component bulk heterojunction concepts due to simplified device fabrication and a dramatically improved microstructure stability. The organic semiconductors used in SCOSCs can be divided into polymeric materials, that is, double-cable polymers, di-block copolymers as well as donor–acceptor small molecules. The nature of donor and acceptor segments, the length and flexibility of the connecting linker and the resultant nanophase separation morphology are the levers which allow optimizing the photovoltaic performance of SCOSCs. While remaining at 1–2% for over a decade, efficiencies of SCOSCs have recently witnessed significant improvement to over 6% for several materials systems and to a record efficiency of 8.4%. In this mini-review, we summarize the recent progress in developing SCOSCs towards high efficiency and stability, and analyze the potential directions for pushing SCOSCs to the next efficiency milestone.

Unraveling the Charge‐Carrier Dynamics from the Femtosecond to the Microsecond Time Scale in Double‐Cable Polymer‐Based Single‐Component Organic Solar Cells

“…Obviously, the design of PBDBPBICl does address the deficiencies of early‐stage SCOSC designs, which suffered from dominant recombination losses expressed in low FF values of ≈0.3 and EQE of ≈20%. [ 10,13,14,39 ]…”

“…Obviously, the design of PBDBPBICl does address the deficiencies of early-stage SCOSC designs, which suffered from dominant recombination losses expressed in low FF values of ≈0.3 and EQE of ≈20%. [10,13,14,39] After detecting charge-carrier dynamics in films, optimized full devices based on PBDBPBICl thermally annealed at 230 °C were then characterized to gain a deeper insight into the photophysics of a double-cable polymer under operational conditions. To analyze charge generation, the photocurrent density (J ph ) as a function of effective voltage (V eff ) was measured as shown in Figure 9A, in which the maximum charge-carrier generation rate G max is calculated to be 6.5 × 10 21 cm -3 s -1 , lower than that of the state-of-theart BHJ system (e.g., PM6:IT-4F, 1.23 × 10 22 cm -3 s -1 ).…”

“…OPV materials used in SCOSCs are generally divided into polymeric (with side‐chain or in‐chain approaches) and molecular (with D–A, D–A–D, or A–D–A structures) semiconductors, as schematically shown in Figure 1 . [ 10,13,14 ] Throughout the early stages, both types of materials exhibited similar performances. Starting from the efficiency around 0.5% before 2009, then staggering at around 2–3% until 2016, [ 10 ] organic semiconductors for SCOSCs experienced a long rugged developing process.…”

“…SCOSCs have significant advantages over multiple‐component BHJ strategies: a considerable simplification of device fabrication in combination with a covalently stabilized active layer morphology, which is expected to give unprecedented thermal stability. [ 10–13 ] In our previous study, we demonstrated that SCOSCs based on a double‐cable polymer are stable even under harsh conditions, such as baking at 160 °C or under continuous illumination at 90 °C, suggesting them as a promising photovoltaic material class for potential applications under harsh conditions. [ 12 ] However, encouraging recent progress should not obscure the fact that the basic scientific principles behind SCOSCs are still to be clarified.…”

Fullerene-Based Triads with Controlled Alkyl Spacer Length as Photoactive Materials for Single-Component Organic Solar Cells

“…Organic solar cells (OSCs) have been extensively investigated over the last 2 decades because of their promising aspects for realizing low-cost solar energy conversion with applicability for flexible and portable devices. − As a result of continuous efforts to develop new photovoltaic materials and the optimization of device fabrication of OSCs based on electron donors (D) and acceptors (A), power conversion efficiencies (PCEs) over 17–18% for single-cell and tandem devices have been reported. − As an interesting approach for simplifying the complexity of morphology control and stability of D/A-blended OSCs, single-component organic solar cells (SCOSCs) have been studied. , They use a single-component (SC) molecule as the photoactive material, which has the p- and n-type D and A units chemically bonded by a covalent linkage. − Using SC photoactive materials can simplify the device fabrication steps, which may improve the reproducibility of device fabrication. The active layer morphology in D/A blends is vulnerable to heat, moisture, and light during device operation, which may degrade the device performance.…”