Search

Further technological development of perovskite solar cells (PSCs) will require improvements in power conversion efficiency and stability, while maintaining low material costs and simple fabrication. In this Research Article, we describe top-illuminated ITO-free, stable PSCs featuring microcavity structures, wherein metal layers on both sides on the active layers exerted light interference effects in the active layer, potentially increasing the light path length inside the active layer. The optical constants (refractive index and extinction coefficient) of each layer in the PSC devices were measured, while the optical field intensity distribution was simulated using the transfer matrix method. The photocurrent densities of perovskite layers of various thicknesses were also simulated; these results mimic our experimental values exceptionally well. To modify the cavity electrode surface, we deposited a few nanometers of ultrathin MoO3 (2, 4, and 6 nm) in between the Ag and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) layers provide hydrophobicity to the Ag surface and elevate the work function of Ag to match that of the hole transport layer. We achieved a power conversion efficiency (PCE) of 13.54% without hysteresis in the device containing a 4 nm-thick layer of MoO3. In addition, we fabricated these devices on various cavity electrodes (Al, Ag, Au, Cu); those prepared using Cu and Au anodes displayed improved device stability of up to 72 days. Furthermore, we prepared flexible PSCs having a PCE of 12.81% after incorporating the microcavity structures onto poly(ethylene terephthalate) as the substrate. These flexible solar cells displayed excellent stability against bending deformation, maintaining greater than 94% stability after 1000 bending cycles and greater than 85% after 2500 bending cycles performed with a bending radius of 5 mm.

Next‐generation photovoltaic technologies such as dye‐sensitized solar cells, organic thin‐film photovoltaics and perovskite solar cells are promising to efficiently harvest ambient light energy. However, more and deeper understanding of their photovoltaic characteristics is essential to create new applications under room light illumination. In this study, for the first time, the difference in temperature coefficients and angular dependence of photovoltaic parameters for the large‐area devices are investigated systematically under the compact fluorescent lamp and light‐emitting diode light. These emerging photovoltaic devices, compared with the single crystalline silicon solar cells, not only have higher open‐circuit voltage (up to approximate 1 V) and better power conversion efficiency (in the range of 9.2% ~ 22.6%) but also exhibit less temperature dependent voltage and output power (< −0.6% °C−1), as well as broader angular response (over 75 degrees). The state‐of‐the‐art dye‐sensitized and organic thin‐film devices also show advantageously positive temperature coefficients of current, and the latter even has positive thermal dependence of fill factor. These features suggest the next‐generation photovoltaic devices are more favorable than the conventional crystalline silicon solar cells for real‐life indoor applications. [ABSTRACT FROM AUTHOR]

Hole transporting layers (HTLs) have critical roles in the performance of perovskite solar cells. In this study, films of the vacuum-deposited small molecule of Tris[4-(5-phenylthiophene-2-yl)phenyl]amine (TPTPA) are demonstrated as efficient HTL materials for perovskite solar cells. The horizontal molecular stacking of the TPTPA neat film leads to the exceptionally high hole drift mobility of 7 × 10 −3 cm 2 V −1 s −1 , among the highest values observed in the organic molecular neat films. By doping with MoO 3 , a clear charge transfer state is formed and the hole mobility further increases to 3.6 × 10 −2 cm 2 V −1 s −1 . Both normal- and inverted-structured perovskite solar cells utilizing these HTLs are prepared and optimized; they show high power conversion efficiencies of 17–18%. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate that the performance of perovskite solar cells can be largely boosted with sub-nm pyridine-containing small-molecule electron interfacial layers. These vacuum-deposited sub-nm layers between perovskites and electron transport layers create a permanent dipole moment that improves the interfacial energy level alignment and facilitates a fast electron sweep-out. With these interfacial layers, the devices exhibit exceptional power conversion efficiencies up to 18.8%, a 25% increase compared to that of the one without the interfacial layer. [ABSTRACT FROM AUTHOR]

Vacuum Fabrication: Efficient Cesium Lead Halide Perovskite Solar Cells through Alternative Thousand-Layer Rapid Deposition (Adv. Funct. Keywords: alternative deposition; cesium; perovskite solar cells; vacuum deposition Alternative deposition, cesium, perovskite solar cells, vacuum deposition. [Extracted from the article]

The novel growth of cesium lead halide perovskite thin films, which are prepared through thousand‐layer rapid alternative deposition, is performed by developing an active perovskite film consisting of a layer‐by‐layer structure. This method is considerably more difficult to be implemented from the solution process. The obtained thin film morphology and characteristics are distinguished from that of the traditional a few layers and two‐material codeposition. These alternative deposited perovskites are integrated with vacuum‐deposited carrier‐transporting layers and electrodes, and all vacuum‐sublimed perovskite solar cells exhibit an outstanding power conversion efficiency of 13.0%. The use of these devices for environmental light energy harvesting provides a power conversion efficiency of 33.9% under fluorescent light illumination of 1000 lux. [ABSTRACT FROM AUTHOR]