application-oriented research like process engineering and upscaling is observed. [1][2][3][4][5] Even though other optoelectronic devices like light emitting diodes and lasers are being researched, [6][7][8][9][10][11][12][13] perovskite-based photovoltaics (PV) is the key technology driving the fast emergence of perovskitebased optoelectronics. Recently, power conversion efficiencies (PCEs) close to 24% were demonstrated for perovskite PV, exceeding the PCEs of established thinfilm technologies. [14] Despite the rapid progress in terms of PCE, one key challenge of perovskite-based PV is still its low stability under realistic outdoor stress conditions-temperature, humidity, and ultraviolet (UV) radiation. A significant advance toward more stable devices was demonstrated by engineering the composition of the large cation site of the perovskite crystal structure and by including low-dimensional perovskite interlayers and passivation layers. [15][16][17][18][19][20] Further advances in stability are based on the charge extracting materials and their interfaces with the perovskite absorber layers. [21][22][23] Most reported record PCEs are still based on highly expensive organic hole transport layer (HTL) materials like 2,2′,7,7′-tetrakis[N,N-di (4methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-MeOTAD) or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA). [20,24,25] Although these materials result in good performance on short High-quality charge carrier transport materials are of key importance for stable and efficient perovskite-based photovoltaics. This work reports on electron-beam-evaporated nickel oxide (NiO x ) layers, resulting in stable power conversion efficiencies (PCEs) of up to 18.5% when integrated into solar cells employing inkjet-printed perovskite absorbers. By adding oxygen as a process gas and optimizing the layer thickness, transparent and efficient NiOx hole transport layers (HTLs) are fabricated, exhibiting an average absorptance of only 1%. The versatility of the material is demonstrated for different absorber compositions and deposition techniques. As another highlight of this work, all-evaporated perovskite solar cells employing an inorganic NiO x HTL are presented, achieving stable PCEs of up to 15.4%. Along with good PCEs, devices with electron-beam-evaporated NiO x show improved stability under realistic operating conditions with negligible degradation after 40 h of maximum power point tracking at 75 °C. Additionally, a strong improvement in device stability under ultraviolet radiation is found if compared to conventional perovskite solar cell architectures employing other metal oxide charge transport layers (e.g., titanium dioxide). Finally, an all-evaporated perovskite solar mini-module with a NiO x HTL is presented, reaching a PCE of 12.4% on an active device area of 2.3 cm 2 .
In this work, we report on indium tin oxide-free, all-solution processed transparent organic light emitting diodes (OLEDs) with inverted device architecture. Conductive polymer layers are employed as both transparent cathodes and transparent anodes, with the top anodes having enhanced conductivities from a supporting stochastic silver nanowire mesh. Both electrodes exhibit transmittances of 80-90% in the visible spectral regime. Upon the incorporation of either yellow- or blue-light emitting fluorescent polymers, the OLEDs show low onset voltages, demonstrating excellent charge carrier injection from the polymer electrodes into the emission layers. Overall luminances and current efficiencies equal the performance of opaque reference OLEDs with indium tin oxide and aluminium electrodes, proving excellent charge carrier-to-light conversion within the device.
In this work, for the first time, the diameter limit of surfactant wrapped single walled carbon nanotubes (SWCNTs) in SWCNT:C60 solar cells is determined through preparation of monochiral small and large diameter nanotube devices as well as those from polychiral mixtures. Through assignment of the different nanotube chiralities by photoluminescence and optical density measurements a diameter limit yielding 0% internal quantum efficiency (IQE) is determined. This work provides insights into the required net driving energy for SWCNT exciton dissociation onto C60 and establishes a family of (n,m) species which can efficiently be utilized in polymer‐free SWCNT:C60 solar cells. Using this approach the largest diameter nanotube with an IQE > 0% is found to be (8,6) with a diameter of 0.95 nm. Possible strategies to extend this diameter limit are then discussed.
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