Abstract
Perovskite solar cells (PSCs) have attracted much attention due to their low-cost fabrication and high power conversion efficiency (PCE). However, the long-term stability issues of PSCs ...remain a significant bottleneck impeding their commercialization. Inverted PSCs with a p-i-n architecture are being actively researched due to their concurrent good stability and decent efficiency. In particular, the PCE of inverted PSCs has improved significantly in recent years and is now almost approaching that of n-i-p PSCs. This review summarizes recent progress in the development of high-efficiency inverted PSCs, including the development of perovskite compositions, fabrication methods, and counter electrode materials (CEMs). Notably, we highlight the development of charge transport materials (CTMs) and the effects of defect passivation strategies on the performance of inverted PSCs. Finally, we discuss the remaining issues and perspectives of high-efficiency inverted PSCs.
Abstract
The long-term stability of perovskite solar cells remains one of the most important challenges for the commercialization of this emerging photovoltaic technology. Here, we adopt a non-noble ...metal/metal oxide/polymer multiple-barrier to suppress the halide consumption and gaseous perovskite decomposition products release with the chemically inert bismuth electrode and Al
2
O
3
/parylene thin-film encapsulation, as well as the tightly closed system created by the multiple-barrier to jointly suppress the degradation of perovskite solar cells, allowing the corresponding decomposition reactions to reach benign equilibria. The resulting encapsulated formamidinium cesium-based perovskite solar cells with multiple-barrier maintain 90% of their initial efficiencies after continuous operation at 45 °C for 5200 h and 93% of their initial efficiency after continuous operation at 75 °C for 1000 h under 1 sun equivalent white-light LED illumination.
Abstract
Despite significant improvements in photo-electricity conversion efficiency of perovskite solar cells (PSCs) over the past several years, this emerging photovoltaic technology is still years ...away from large-scale commercial application. In this review, important research progresses on PSCs’ ‘golden triangle’ parameters of efficiency, stability, and cost in literatures were objectively analyzed. We focused on their key bottlenecks and distinct contradictions hindering their fast commercialization. We also proposed the most urgent directions requiring intensive research and development input in the coming years to speed up the commercialization process of PSCs.
Organic ammonium salts have been widely used for defect passivation to suppress nonradiative charge recombination in perovskite solar cells (PSCs). However, they are prone to form undesirable ...in‐plane favored 2D perovskites with poor charge transport capability that hamper device performance. Herein, the defects passivation role of alkyldiammonium including 1.6‐hexamethylenediamine dihydriodide (HDAI2), 1,3‐propanediamine dihydriodide (PDAI2), and 1.4‐butanediamine dihydriodide (BDAI2) for formamidinium‐cesium perovskite is systematically investigated. With help of density functional theory (DFT) calculations, BDA with suitable size can synergistically passivate two defect sites on perovskite surfaces, showing the best defect passivation effect among the above three alkyldiammonium salts. Perovskite films based on BDAI2 modification are found to keep the 3D perovskite phase with considerably reduced trap‐state density, and enhanced carrier extraction. As a result, the BDAI2‐modified devices deliver impressive efficiencies of 23.1% and 20.9% for inverted PSCs on the rigid and flexible substrates, respectively. Moreover, the corresponding encapsulated rigid devices maintain 92% of the initial efficiency after operating under continuous 1‐sun illumination with the maximum power point tracking for 1000 h. Furthermore, the mechanical flexibility of the BDAI2‐modified flexible device is also improved due to the release of residual stress.
BDA can make full use of the two ammonium cations for passivation and strengthen the absorption of BDA onto the VFA defect as well as enhance the formation energy of VFA, and thereby anchor the perovskite surfaces, so as to improve the photovoltaic performance of rigid and flexible devices.
Inverted perovskite solar cells (PSCs) based on formamidinium-cesium (FACs) perovskites with nickel oxide as hole transport layer (HTL) have attracted much attention due to their good stability. ...However, their open-circuit voltage (VOC) and efficiencies lag far behind those of inverted PSCs based on organic HTLs. Here, we introduce an organic dye coumarin 343 (C343) as a molecular additive into the perovskite to reduce VOC loss and improve the efficiency of nickel oxide-based inverted PSCs. We demonstrate that the strong coordination between the carboxyl groups in C343 and under-coordinated Pb2+ not only optimizes perovskite crystal growth during perovskite formation, but also reduces the defects densities within perovskite films. As a result, our C343 doped PSCs achieve an optimal efficiency of 20.9% (certified 20.2%), which is one of the highest efficiencies for FACs perovskite and nickel oxide based inverted PSCs reported so far. Moreover, the utilization of C343 also benefits devices’ stability, making the devices maintain over 94% and 95% of the initial PCE after aging at 85 °C for 500 h in N2 glovebox and operation under continuous 1 sun illumination with the maximum power point (MPP) tracking at the temperature around 65 °C in ambient air for 500 h, respectively.
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•Coumarin 343 can optimize perovskite crystal growth and passivate defects by its coordination with uncoordinated Pb2+ ions.•Coumarin 343 is demonstrated to improve the thermal stability and operational stability of the devices.•PCEs up to 20.94% (certified 20.2%) are achieved for nickel oxide-based formamidinium-cesium perovskite solar cells.
Perovskite solar cells (PSCs) require both high efficiency and reliable long-term stability for commercialization. As important as the perovskite layer, charge transport layers and their contact with ...the adjacent perovskite layer also play crucial roles in the efficiency and stability of PSCs. Herein, we report the use of pyridine anchoring group functionalized poly(triarylamine) (p-PY) as the hole transport layer at buried interfaces between the conductive oxide substrate and formamidinium-cesium perovskite layer to enhance the efficiency and stability of inverted PSCs. The p-PY based device exhibited a record efficiency of 22.8% (certified efficiency of 22.3%) and maintained 97.5% of the initial efficiency after operation under 1 sun equivalent white-light light-emitting diode array illumination with maximum power point tracking at 45 °C for 1000 h, and 94% and 81% of the initial efficiencies after harsh thermal aging at 85 °C for 500 h and at 120 °C for 200 h, respectively.
Herein, we report the use of pyridine anchoring group functionalized poly(triarylamine) (p-PY) as a hole transport layer at buried interfaces between the ITO and formamidinium-cesium perovskite layer to enhance the efficiency and stability of inverted PSCs.
In perovskite solar cells, the formation of residual/excess lead iodide (PbI
2
) in the perovskite film is detrimental to device stability. However, the understanding of the effect of residual/excess ...PbI
2
and its distribution on perovskite degradation is still insufficient. Herein, we verify that the existence of residual PbI
2
near the buried interface largely deteriorates perovskite stability. By using a pre-embedding mixed A-cation halide strategy, the residual unstable PbI
2
near the buried interface is transformed into a more stable 3D perovskite for stability improvement. Moreover, this strategy could balance the lattice strain of the formamidinium-based perovskite near the buried interface, suppress the detrimental α to δ phase transition and improve perovskite phase stability. As a result, promising power conversion efficiencies of 24.26% and 20.97% are obtained for perovskite solar cells and modules, respectively. In addition, the solar cells maintain 94.7% of their initial efficiencies after operating for 1000 hours under one sun illumination.
A pre-embedding mixed A-cation halide strategy is developed to eliminate the residual unstable PbI
2
and lattice strain near the buried interface of the perovskite layer for the stability improvement of formamidinium-based perovskite solar cells.
Presently, perovskite solar cells (PSCs) have emerged as one of the most prominent photovoltaic (PV) technologies. However, the stability of PSCs is typically the primary challenge hindering their ...practical application. Among the various factors that affect PSC stability, potential-induced degradation (PID) is recognized as a significant reliability threat and can cause considerable damage to PSCs within a short timeframe. Accordingly, herein, we aim to review the progress on PID, its associated mechanisms, contributing environmental factors, and testing techniques by mainly focusing on various present PV technologies. Further, studies on PID are reviewed and valuable insights are offered for future research endeavors related to PID in PSCs and associated modules. Moreover, to enhance the commercialization aspects of PSCs, studies on the impact of structural and compositional characteristics, methodologies for the mitigation of environmental stressors, and the importance of interfacial engineering as future emerging trends are discussed.
Potential-induced degradation, a major factor in solar cell stability, is a reliability threat that can damage them within a shorter timeframe. As a promising and emerging PV technology, perovskite solar cells must overcome PID to be commercialized.
Lead halide‐based perovskites solar cells (PSCs) are intriguing candidates for photovoltaic technology due to their high efficiency, low cost, and simple fabrication processes. Currently, PSCs with ...efficiencies of >25% are mainly based on methylammonium (MA)‐free and bromide (Br) free, formamide lead iodide (FAPbI3)‐based perovskites, because MA is thermally unstable due to its volatile nature and Br incorporation will induce blue shift in the absorption spectrum. Therefore, MA‐free, Br‐free formamidine‐based perovskites are drawing huge research attention in recent years. The hole transporting layer (HTL) is crucial in fabricating highly efficient and stable inverted p‐i‐n structured PSCs by enhancing charge extraction, lowering interfacial recombination, and altering band alignment, etc. Here, this work employs a NiOx/PTAA bi‐layer HTL combined with GuHCl (guanidinium hydrochloride) additive engineering and PEAI (phenylethylammonium iodide) passivation strategy to optimize the charge carrier dynamics and tune defects chemistry in the MA‐free, Br‐free RbCsFAPbI3‐based perovskite absorber, which boosts the device efficiency up to 22.78%. Additionally, the device retains 95% of its initial performance under continuous 1 sun equivalent LED light illumination at 45 °C for up to 500 h.
This work focuses on using a bi‐interfacial HTL strategy and additive engineering to modulate the performance of MA, Br‐free formamidine‐based perovskite solar cells. Inverted structured devices with NiOx‐based HTLs achieve a high VOC of 1.14 V and efficiency of 22.78%.
•A finely-controlled CVD deposition of hydrophobic Parylene C polymer is conducted to form the interlayer in inverted PSCs.•Parylene polymer can also serve as a wide-bandgap and insulated tunneling ...layer to inhibit interfacial charge recombination and benefit the charge transfer and the chloride group chemically react with the undercoordinated lead centers and decrease the defects of the device.•The Parylene C modified devices yield impressive long-term stability and reproducibility, both of which are important features urgently required by the industrialization of PSCs.
Perovskite solar cells (PSCs) have been shining in the photovoltaic industry, but their fragile stability impedes their commercialization seriously. Here we adopt an ultra-thin film of a functional hydrophobic polymer, polychloro-p-dimethyl benzene (Parylene C), which can largely improve the operational lifetime of PSCs as a surface finish. Chemical vapor deposition (CVD) under vacuum is adopted to modify the ultra-thin parylene film, which is thin adequately to afford tunnel contact but is also sufficiently shielding to protect the perovskite layer. Besides, it is demonstrated that the Parylene C film can reduce the perovskite surface defects by interacting with the uncoordinated Pb center and act as an effective hole-hindering barrier in the middle of perovskite and PCBM for decreasing charge recombination. As a result, PSC using a ∼4 nm Parylene C layer exhibits a remarkably increased open-circuit and fill factor and a substantially enhanced efficiency of 21.7 % from pristine 19.4 %. Moreover, the Parylene C-based PSCs have attained long-term thermal and operational stabilities with good reproducibility. Without encapsulation, the degradation was limited to 11 % after 500 h of aging under ambient atmosphere/dark, 85 °C/N2, or constant illumination/ N2 conditions. This work lays a solid foundation for further stability by CVD interface modification.
