A Review of Perovskites Solar Cell Stability

Additive Engineering for Efficient and Stable Perovskite Solar Cells

Current-density-voltage (J-V) hysteresis in perovskite solar cells (PSCs) is a critical issue because it is related to power conversion efficiency and stability. Although parameters affecting the hysteresis have been already reported and reviewed, little investigation is reported on scan-direction-dependent J-V curves depending on perovskite composition. This review investigates J-V hysteric behaviors depending on perovskite composition in normal mesoscopic and planar structure. In addition, methodologies toward hysteresis-free PSCs are proposed. There is a specific trend in hysteresis in terms of J-V curve shape depending on composition. Ion migration combined with nonradiative recombination near interfaces plays a critical role in generating hysteresis. Interfacial engineering is found to be an effective method to reduce the hysteresis; however, bulk defect engineering is the most promising method to remove the hysteresis. Among the studied methods, KI doping is proved to be a universal approach toward hysteresis-free PSCs regardless of perovskite composition. It is proposed from the current studies that engineering of perovskite film near the electron transporting layer (ETL) and the hole transporting layer (HTL) is of vital importance for achieving hysteresis-free PSCs and extremely high efficiency.

On the Current-Voltage Hysteresis in Perovskite Solar Cells: Dependence on Perovskite Composition and Methods to Remove Hysteresis

Recently, perovskite solar cells (PSCs) have attracted much attention owing to their high power conversion efficiency (25.2%) and low fabrication cost. However, the short lifetime under operation is the major obstacle for their commercialization. With efforts from the entire PSC research community, significant advances have been witnessed to improve the device operational stability, and a timely summary on the progress is urgently needed. In this review, we first clarify the definition of operational stability and its significance in the context of practical use. By analyzing the mechanisms in established approaches for operational stability improvement, we summarize several effective strategies to extend device lifetime in a layer-by-layer sequence across the entire PSC. These mechanisms are discussed in the contexts of chemical reactions, photo-physical management, technological modification, etc., which may inspire future R&D for stable PSCs. Finally, emerging operational stability standards with respect to testing and reporting device operational stability are summarized and discussed, which may help reliable device stability data circulate in the research community. The main target of this review is gaining insight into the operational stability of PSCs, as well as providing useful guidance to further improve their operational lifetime by rational materials processing and device fabrication, which would finally promote the commercialization of perovskite solar cells.

Towards commercialization: the operational stability of perovskite solar cells

The significance of graphene and its two-dimensional (2D) analogous inorganic layered materials especially as hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS2) for “clean energy” applications became apparent over the last few years due to their extraordinary properties. In this review article we study the current progress and selected challenges in the syntheses of graphene, h-BN and MoS2 including energy storage applications as supercapacitors and batteries. Various substrates/catalysts (metals/insulator/semiconducting) have been used to obtain graphene, h-BN and MoS2 using different kinds of precursors. The most widespread methods for synthesis of graphene, h-BN and MoS2 layers are chemical vapor deposition (CVD), plasma-enhanced CVD, hydro/solvothermal methods, liquid phase exfoliation, physical methods etc. Current research has shown that graphene, h-BN and MoS2 layered materials modified with metal oxide can have an insightful influence on the performance of energy storage devices as supercapacitors and batteries. This review article also contains the discussion on the opportunities and perspectives of these materials (graphene, h-BN and MoS2) in the energy storage fields. We expect that this written review article including recent research on energy storage will help in generating new insights for further development and practical applications of graphene, h-BN and MoS2 layers based materials.

A review on synthesis of graphene, h-BN and MoS 2 for energy storage applications: Recent progress and perspectives

As one kind of promising next-generation photovoltaic devices, perovskite solar cells (PVSCs) have experienced unprecedented rapid growth in device performance over the past few years. However, the practical applications of PVSCs require much improved device long-term stability and performance, and internal defects and external humidity sensitivity are two key limitation need to be overcome. Here, gadolinium fluoride (GdF3 ) is added into perovskite precursor as a redox shuttle and growth-assist; meanwhile, aminobutanol vapor is used for Ostwald ripening in the formation of the perovskite layer. Consequently, a high-quality perovskite film with large grain size and few grain boundaries is obtained, resulting in the reduction of trap state density and carrier recombination. As a result, a power conversion efficiency of 21.21% is achieved with superior stability and negligible hysteresis.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.201904347

Suppressing Vacancy Defects and Grain Boundaries via Ostwald Ripening for High-Performance and Stable Perovskite Solar Cells.

Spiro-OMeTAD as a hole-transport material (HTM) plays a crucial role in the photovoltaic performance and stability of perovskite solar cells (PSCs). However, the inferior conductivity and mediocre hole-mobility of unoxidized spiro-OMeTAD limit its function. In order to improve the functional properties of HTMs, we develop a new kind of dopant, vanadic oxide (V2O5) in place of the traditional oxygen in the presence of a lithium salt. V2O5 with strong redox potential can rapidly oxidize spiro-OMeTAD, which effectively improves the hole-transport properties and adjusts the energy level of the HTM. Consequently, the champion PSC based on the V2O5-doped HTM achieves a power conversion efficiency of 20.5%, while the device without V2O5 doping exhibits an efficiency of 18.1% under the same test conditions. Meanwhile, owing to the reduction of trap state density and the band gap adjustment by V2O5 doping the hysteresis of devices is effectively suppressed and the stability is improved. The facile and inexpensive treatment and obvious performance improvement render the present finding very promising.

High performance and stable perovskite solar cells using vanadic oxide as a dopant for spiro-OMeTAD

High performance perovskite solar cells based on β-NaYF4:Yb3+/Er3+/Sc3+@NaYF4 core-shell upconversion nanoparticles

Pyridine solvent engineering for high quality anion-cation-mixed hybrid and high performance of perovskite solar cells

The quality of the perovskite layer has an important influence on the photovoltaic performance and stability of perovskite solar cells. An appropriate additive can effectively improve the quality of perovskites. In this work, pyrrole is introduced into a cesium-containing triple cation perovskite precursor solution and this strategy is demonstrated to control the crystallinity of perovskite films. The pyrrole ring is hydrophobic, and its nitrogen atom (N) can combine with the lead–iodine (Pb–I) framework by coordinating with Pb ions or pyrrole forms hydrogen bonds with organic cations. XRD patterns and AFM images prove that pyrrole significantly affects the crystallinity and roughness of perovskite films. The pyrrole-modified device exhibits a champion power conversion efficiency of 20.07%, while the pristine device has an efficiency of 18.58% under the same conditions. This approach suggests an important direction for improving the film quality to reduce trap density and charge recombination.

Qiyao Guo

Papers

Suppressing Vacancy Defects and Grain Boundaries via Ostwald Ripening for High-Performance and Stable Perovskite Solar Cells.

High performance and stable perovskite solar cells using vanadic oxide as a dopant for spiro-OMeTAD

High performance perovskite solar cells based on β-NaYF4:Yb3+/Er3+/Sc3+@NaYF4 core-shell upconversion nanoparticles

Pyridine solvent engineering for high quality anion-cation-mixed hybrid and high performance of perovskite solar cells

Pyrrole: an additive for improving the efficiency and stability of perovskite solar cells