Fullerene‐Based Interlayers for Breaking Energy Barriers in Organic Solar Cells

Abstract

cells (OSCs) are lightweight, flexible, and have easy solution processability, thus making them advantageous for large-area device fabrication. The interlayer materials between the electrodes and organic active layer are vital elements for device fabrication. Recently, solution-processable fullerene derivatives have been studied intensively as efficient electrode interlayer materials for solar cell applications. In this Minireview, we summarize recent advances using fullerene derivatives as interlayers in OSCs. The examples include full-erene interlayers from small molecules to polymers, and to organic composites or organic/inorganic hybrid materials. We focus on the comprehensive efforts in developing fullerenebased interlayers and present the understanding of multiple functionalities of these materials as cathode interlayers in bulk hetero-junction (BHJ) OSCs. Our motivation is to describe our current understanding, recent progress, and outstanding issues of fullerene interlayers in OSCs, and propose future potential directions and opportunities.[a] Y.

Excitons Dominate the Emission from PM6:Y6 Solar Cells, but This Does Not Help the Open-Circuit Voltage of the Device

“…Given the small differences between the EL and PL spectral shapes, but the rather large difference in intensity, the question arises whether conclusions from the analysis of the EL spectra are representative of the state population in the active layer under photoexcitation at V OC conditions. For example, the EL efficiency can be easily affected by injection barriers, while the bulk and surface density of photogenerated carriers may be reduced by non-selective contacts . To ensure that both driving conditions create the same free carrier population, we compared the results from steady-state photoinduced absorption (PIA) and electromodulation injection absorption (EMIA) spectroscopy on the very same device.…”

Recent Progress in Organic Solar Cells: A Review on Materials from Acceptor to Donor

“…Besides the material itself, other factors, including device structure [ 22 , 146 , 147 , 148 ], film morphology [ 149 , 150 ], stability [ 151 , 152 , 153 ], and so on, play important roles in the development and application of OSCs as well. For the optimization of device structure, besides the ternary and tandem structure presented in this review, interfacial modification and surface texturization are also efficient approaches for obtaining high-performance OSCs [ 148 , 154 ]. Limited by the short diffusion length of exciton in organic semiconductor materials [ 155 ], the issue of film morphology of the active layer is one of the crucial factors when fabricating highly efficient devices in BHJ-OSCs.…”

Perylene‐diimide‐based cathode interlayer materials for high performance organic solar cells

“…27 However, the p-type nature of polyfluorene of PFN main chains and insulating properties of the nonconjugated organic molecules are undesirable for electron transport through the cathode interlayer. Therefore, n-type conjugated molecules with high electron affinity and high electron mobility, such as functional fullerenes, 28,29 n-doped carbon nanotubes and graphene, 20,30,31 naphthalene diimides (NDIs), [32][33][34][35] and perylene diimides (PDIs), [36][37][38] are more suitable and efficient as CIMs for modifying the cathode.…”