Heterojunction modification for highly efficient organic-inorganic perovskite solar cells

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

Efficient lead halide perovskite solar cells use hole-blocking layers to help collection of photogenerated electrons and to achieve high open-circuit voltages. Here, we report the realization of efficient perovskite solar cells grown directly on fluorine-doped tin oxide-coated substrates without using any hole-blocking layers. With ultraviolet-ozone treatment of the substrates, a planar Au/hole-transporting material/CH₃NH₃PbI₃-xClx/substrate cell processed by a solution method has achieved a power conversion efficiency of over 14% and an open-circuit voltage of 1.06 V measured under reverse voltage scan. The open-circuit voltage is as high as that of our best reference cell with a TiO₂ hole-blocking layer. Besides ultraviolet-ozone treatment, we find that involving Cl in the synthesis is another key for realizing high open-circuit voltage perovskite solar cells without hole-blocking layers. Our results suggest that TiO₂ may not be the ultimate interfacial material for achieving high-performance perovskite solar cells.

Zr Incorporation into TiO2 Electrodes Reduces Hysteresis and Improves Performance in Hybrid Perovskite Solar Cells while Increasing Carrier Lifetimes

We investigate zirconium (Zr) incorporation into the titanium dioxide (TiO2) electron-transporting layer used in organometal halide perovskite photovoltaics. Compared to Zr-free controls, solar cells employing electrodes containing Zr exhibit increased power conversion efficiency (PCE) and decreased hysteresis. We use transient photovoltage and photocurrent extraction to measure carrier lifetimes and densities and observe longer carrier lifetimes and higher charge densities in devices on Zr-containing electrodes at microsecond times as well as longer persistent photovoltages extending from ∼milliseconds to tens of seconds. We characterize the surface stoichiometry and change in work function and reduction potential of the TiO2 upon incorporation of Zr and discuss the charge recombination at the TiO2 interface in the context of these variables. Finally, we show that the combination of Zr-TiO2 electrode modification with device pyridine treatment leads to a cumulative improvement in performance.

Novel spiro-based hole transporting materials for efficient perovskite solar cells

Three spiro-acridine-fluorene based hole transporting materials (HTMs), namely CW3, CW4 and CW5, are employed in the fabrication of organic–inorganic hybrid perovskite solar cells.

Improved charge transport and injection in a meso-superstructured solar cell by a tractable pre-spin-coating process

By pre-spin-coating a perovskite precursor solution, increased perovskite capacity in the mesoporous structure, enhanced electron injection and more charge transport pathways are realized.

Interfacial engineering by using self-assembled monolayer in mesoporous perovskite solar cell

A self-assembled monolayer of 4-aminobenzoic acid (PABA) modified TiO₂ layer improved the interfacial compatibility and the quality of the above-deposited perovskite, leading to the power conversion efficiency of the device to be enhanced to 10.58%.