Perovskite (structure)

About: Perovskite (structure) is a research topic. Over the lifetime, 51482 publications have been published within this topic receiving 1541750 citations.

Functionalization of perovskite thin films with moisture-tolerant molecules

Abstract: Organic–inorganic hybrid perovskites are particularly suited as light-harvesting materials in photovoltaic devices. The power conversion efficiency of perovskite solar cells has reached certified values of over 20% in just a few years. However, one of the major hindrances for application of these materials in real-world devices is the performance degradation in humid conditions, leading to a rapid loss of photovoltaic response. Here, we demonstrate that hydrophobic tertiary and quaternary alkyl ammonium cations can be successfully assembled on the perovskite surface as efficient water-resisting layers via a facile surface functionalization technique. Such layers can protect the perovskite film under high relative humidity (90 ± 5%) over 30 days. More importantly, devices based on such films can retain the photovoltaic capacities of bulk perovskites, with power conversion efficiencies over 15%. Improving the humidity tolerance of perovskite materials is a necessary step towards large-scale production of high-performance perovskite-based devices under ambient humidity. Organic–inorganic perovskites are promising materials for photovoltaic devices, however they have poor tolerance to ambient humidity. Now, their surface can be functionalized with water-resistant molecules to stabilize their performance under humid conditions.

Extrinsic ion migration in perovskite solar cells

Abstract: The migration of intrinsic ions (e.g., MA+, Pb2+, I−) in organic–inorganic hybrid perovskites has received significant attention with respect to the critical roles of these ions in the hysteresis and degradation in perovskite solar cells (PSCs). Here, we demonstrate that extrinsic ions (e.g., Li+, H+, Na+), when used in the contact layers in PSCs, can migrate across the perovskite layer and strongly impact PSC operation. In a TiO2/perovskite/spiro-OMeTAD-based PSC, Li+-ion migration from spiro-OMeTAD to the perovskite and TiO2 layer is illustrated by time-of-flight secondary-ion mass spectrometry. The movement of Li+ ions in PSCs plays an important role in modulating the solar cell performance, tuning TiO2 carrier-extraction properties, and affecting hysteresis in PSCs. The influence of Li+-ion migration was investigated using time-resolved photoluminescence, Kelvin probe force microscopy, and external quantum efficiency spectra. Other extrinsic ions such as H+ and Na+ also show a clear impact on the performance and hysteresis in PSCs. Understanding the impacts of extrinsic ions in perovskite-based devices could lead to new material and device designs to further advance perovskite technology for various applications.

Thin single crystal perovskite solar cells to harvest below-bandgap light absorption

Abstract: The efficiency of perovskite solar cells has surged in the past few years, while the bandgaps of current perovskite materials for record efficiencies are much larger than the optimal value, which makes the efficiency far lower than the Shockley-Queisser efficiency limit. Here we show that utilizing the below-bandgap absorption of perovskite single crystals can narrow down their effective optical bandgap without changing the composition. Thin methylammonium lead triiodide single crystals with tuned thickness of tens of micrometers are directly grown on hole-transport-layer covered substrates by a hydrophobic interface confined lateral crystal growth method. The spectral response of the methylammonium lead triiodide single crystal solar cells is extended to 820 nm, 20 nm broader than the corresponding polycrystalline thin-film solar cells. The open-circuit voltage and fill factor are not sacrificed, resulting in an efficiency of 17.8% for single crystal perovskite solar cells.

High-Purity Inorganic Perovskite Films for Solar Cells with 9.72 % Efficiency.

Abstract: All-inorganic perovskite solar cells with high efficiency and improved stability are promising for commercialization. A multistep solution-processing method was developed to fabricate high-purity inorganic CsPbBr3 perovskite films for use in efficient solar cells. By tuning the number of deposition cycles (n) of a CsBr solution, the phase conversion from CsPb2 Br5 (n ≤3), to CsPbBr3 (n=4), and Cs4 PbBr6 (n≥5) was optimized to achieve vertical- and monolayer-aligned grains. Upon interfacial modification with graphene quantum dots, the all-inorganic perovskite solar cell (without a hole-transporting layer) achieved a power conversion efficiency (PCE) as high as 9.72 % under standard solar illumination conditions. Under challenging conditions, such as 90 % relative humidity (RH) at 25 °C or 80 °C at zero humidity, the optimized device retained 87 % PCE over 130 days or 95 % over 40 days, compared to the initial efficiency.

Ultra-Low Thermal Conductivity in Organic-Inorganic Hybrid Perovskite CH3NH3PbI3

Abstract: We report on the temperature dependence of thermal conductivity of single crystalline and polycrystalline organometallic perovskite CH3NH3PbI3. The comparable absolute values and temperature dependence of the two samples’ morphologies indicate the minor role of the grain boundaries on the heat transport. Theoretical modeling demonstrates the importance of the resonant scattering in both specimens. The interaction between phonon waves and rotational degrees of freedom of CH3NH3+ sublattice emerges as the dominant mechanism for attenuation of heat transport and for ultralow thermal conductivity of 0.5 W/(Km) at room temperature.