Mesoporous Perovskite Solar Cells Research Articles

Efficient inorganic solid solar cells composed of perovskite and PbS quantum dots.

Lead halide perovskite solar cells have attracted great interest due to their high efficiency and simple fabrication process. However, the high efficiency heavily relies on expensive organic hole-transporting materials (OHTMs) such as 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-MeOTAD), it is preferable to replace these expensive OHTMs by inorganic and low cost materials. Here, we report colloidal PbS quantum dots synthesized by a facile method and used as the inorganic hole-transporting material in a hybrid perovskite solar cell. By controlling the crystalline morphology of the perovskite capping layer, the recombination process is significantly retarded. Furthermore, a pure inorganic solar cell prepared by a two-step process demonstrated a nearly 8% power conversion efficiency due to efficient charge separation by a cascade of junctions and retarding charge recombination by a void-free capping layer. The stability of the inorganic solar cell was also tested with a little decay observed within ca. 100 h.

Novel hole transporting materials based on triptycene core for high efficiency mesoscopic perovskite solar cells

Three novel hole-conducting molecules (T101, T102 and T103) based on a triptycene core have been synthesized using short routes with high yields. The optical and electrochemical properties were tuned by modifying the functional groups, through linking the triptycene to diphenylamines via phenyl and/or thienyl groups. The mesoporous perovskite solar cells fabricated using T102 and T103 as the hole transporting material (HTM) showed a power conversion efficiency (PCE) of 12.24% and 12.38%, respectively, which is comparable to that obtained using the best performing HTM spiro-OMeTAD. The T102 based device showed higher fill factor (69.1%) and Voc (1.03 V) than the spiro-OMeTAD based device (FF = 63.4%, Voc = 0.976 V) whereas the T103 based device showed comparable Jsc (20.3 mA cm−2) and higher Voc (0.985 V) than the spiro-OMeTAD (Jsc = 20.8 mA cm−2) based cell.

The Importance of Perovskite Pore Filling in Organometal Mixed Halide Sensitized TiO2-Based Solar Cells.

Emerging from the field of dye-sensitized solar cells, organometal halide perovskite-based solar cells have recently attracted considerable attention. In these devices, the perovskite light absorbers can also be used as charge transporting materials, changing the requirements for efficient device architectures. The perovskite deposition can vary from merely sensitizing the TiO2 electron transporting scaffold as an endowment of small nanoparticles, to completely filling the pores where it acts as both light absorber and hole transporting material in one. By decreasing the TiO2 scaffold layer thickness, we change the solar cell architecture from perovskite-sensitized to completely perovskite-filled. We find that the latter case leads to improvements in device performance because higher electron densities can be sustained in the TiO2, improving electron transport rates and photovoltage. Importantly, the primary recombination pathway between the TiO2 and the hole transporting material is blocked by the perovskite itself. This understanding helps to rationalize the high voltages attainable on mesoporous TiO2-based perovskite solar cells.

Mesoporous perovskite solar cells: material composition, charge-carrier dynamics, and device characteristics.

We report on our investigations on charge transport and recombination in TiO(2)-based mesoporous solar cells using PbI(2) and various perovskite compositions, including CH(3)NH(3)PbI(3), CH(3)NH(3)PbI(2)Br, CH(3)NH(3)PbIBr(2), and CH(3)NH(3)PbBr(3). The mesoporous TiO(2) film is about 650 nm thick. Electron microscopy measurements show that no perovskite capping layer is formed on the top surface of the TiO(2) film. Intensity-modulated photocurrent/photovoltage spectroscopies show that the electron diffusion coefficient and recombination lifetime are governed by the underlying mesoporous TiO(2) film and thus do not depend on the perovskite composition. However, replacing the perovskite absorber with PbI(2) leads to a diffusion coefficient that is about a factor of 5 slower than that in perovskite-based devices. We also find that TiCl(4) treatment of the mesoporous TiO(2) film prior to device fabrication substantially reduces the charge recombination kinetics in mesoporous perovskite solar cells.

The effect of radiation on silicon solar-energy converters : Loferski, J. J.; Rappaport, P., RCA Rev.19(4): 536–554, Dec. 1958. Illus.

We investigated the effect of a compact TiO2 (c-TiO2) layer on the structural, optical, and performance characteristics of mesoporous perovskite solar cells (mp-PSCs) with fluorine-doped tin oxide (FTO)/mesoporous TiO2 with or without c-TiO2 layer/perovskite/spiro-OMeTAD/Au structure. The mp-PSCs with the c-TiO2 layer exhibited a dense and pinhole-free perovskite film with a highly crystalline structure. On the other hand, the mp-PSCs without the c-TiO2 layer suffered from severe recombination problems at the perovskite/FTO interface, which was examined by impedance spectroscopy analysis. However, the c-TiO2 layer of the mp-PSCs played a significant role in reducing the recombination of carriers, due to the high carrier recombination resistance at the perovskite/FTO interface. As a result, the mp-PSCs with the c-TiO2 layer showed a high conversion efficiency of 15.51%, together with an open-circuit voltage of 1.04 V, a short-circuit current density of 20.44 mA/cm2 and a fill factor of 72.73%. In addition, the c-TiO2 layer minimized the hysteresis in the current density-voltage (J-V) curves measured for the mesoporous perovskite solar cells.