Organic-inorganic metal halide perovskite solar cells (PVSCs) have experienced rapid development in recent years, with its power conversion efficiency (PCE) improving from 3.8% in 2009 to an impressive 25.7% in 2021. [1] Thus, the metal halide perovskite is currently considered as a promising emerging photovoltaic (PV) material due to its excellent optoelectronic properties such as high optical absorption coefficient, long charge carrier lifetime, and low nonradiative recombination rates. [2] It is believed that the PVSCs can enter the specific PV market segments, such as building-integrated PV, in the coming years after upscaling the device fabrication and achieving decent device operational stability.The pioneer work of PVSCs was conducted by Miyasaka et al. using CH 3 NH 3 PbBr 3 and CH 3 NH 3 PbI 3 as photoactive materials in the liquid-based dye-sensitized solar cells (DSSCs). [3] The perovskite-based DSSCs achieved an efficiency of 3.8% but exhibited very poor stability because the metal halide perovskites are chemically reactive to the liquid electrolyte. Subsequently, the PCE of perovskite-based DSSCs was further improved to 6.5% using CH 3 NH 3 PbI 3 quantum dots (QDs) as the light absorber in 2011. Although the authors demonstrated enhanced efficiency by this way, the device performance degraded by 80% upon continuous irradiation for only 10 min, because the redox electrolyte dissolved the perovskite QDs due to its strong polar property. [4] To resolve this issue, Park et al. proposed a transition from DSSC to a solid-state PVSC by introducing a solid-state organic hole conductor, namely, 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9-9'spirobifluorene (spiro-OMeTAD). The solid-state hole conductor provides efficient hole extraction from the perovskite layer to the electrode, achieving a record PCE of 9.7%. [5] In addition, the stability of such solid-state PVSCs has improved to over 500 h under AM 1.5 G light illumination. This research has triggered rapid progress in the research activities on PVSCs and the related publications have increased exponentially since 2012. The yearly progress of PVSC is summarized in Figure 1 and the current certified record PCE of PVSCs is 25.7%, achieved by Ulsan National Institute of Science and Technology (UNIST) in 2021. [1]
Potential‐induced degradation (PID) is an important reliability issue of photovoltaic modules. For future field applications of perovskite photovoltaic modules, it is important to study the PID behavior under real‐world operating conditions, which has not yet been thoroughly researched. This work presents PID investigation of glass‐encapsulated perovskite solar cells (PSCs) at different stress conditions for an extended duration of 55 h. At room condition (25 °C, 20% relative humidity [RH]) the efficiency is reduced by 59% when −1000 V is applied to the short‐circuited PSCs, whereas under elevated stress condition (60 °C, 60% RH) the device efficiency suffers severe degradation of >90%. The PID effects are analyzed with several characterization methods, revealing that Na+ ion migration from the front glass pane toward the perovskite layer causes the degradation. Application of a reverse voltage bias right after PID results in very poor recovery under elevated condition compared to the recovery of devices under room condition. It is proposed that PID and its recovery rate depend on the external stress conditions and the reverse bias strategy is not sufficient for the recovery. Possible mitigation strategies which can open a new avenue for further research on PID in PSCs are also presented.
Metal-halide perovskite solar cells (PSCs) have achieved remarkable power conversion efficiencies in recent years, and spiro-OMeTAD plays a significant role as a hole transport material in PSCs with record efficiencies. However, further studies and systematic experimental procedures on doped spiro-OMeTAD are required to enable a reliable process for potential commercialization. In particular, the effect of the prolonged oxidation of Co(III)TFSI co-doped spiro-OMeTAD has been one of the unanswered topics in PSC research. In this work, we investigate the influence of overnight oxidation on the performance of PSCs with Co(III)TFSI co-doped spiro-OMeTAD. Co-doping spiro-OMeTAD with Co(III) complexes instantly oxidizes spiro-OMeTAD, leading to an improvement in power conversion efficiency (PCE) from 13.1% (LiTFSI-doped spiro-OMeTAD) to 17.6% (LiTFSI + Co(III)TFSI-doped spiro-OMeTAD). It is found that PSCs with spiro-OMeTAD co-doped with Co(III)TFSI without overnight oxidation could retain around 90% of the efficiency under maximum power point tracking at 1-sun illumination for 3000 min, whereas the efficiencies drop by more than 30% when Co(III)TFSI co-doped spiro-OMeTAD is exposed to overnight oxidation. Hence, it is important to inhibit the unnecessary overnight oxidation of Co(III)TFSI co-doped spiro-OMeTAD so as to save excess fabrication time and overcome the poor stability issues.
Background/aim: The objective of the paper was to develop a comprehensive “Adolescence Stress Scale” and to examine different psychometric issues in the development, initial validation, and standardization of this scale. Method: Exploratory factor analysis was conducted on the data procured from a sample of 634 (11–18 years) school-going adolescents in India. Results: An exploratory analysis provided a 10 factor structure, namely, major loss induced stress, enforcement or conflict induced stress, phobic stress, interpersonal conflict induced stress, punishment induced stress, illness and injury induced stress, performance stress, imposition induced stress, insecurity induced stress, unhealthy environment induced stress. The 10 oblique factor solutions are found to be interrelated and interdependent with good indices of internal consistency, and content validity. Conclusions: This scale development is a novel and powerful measure that taps onto various aspects of stress experienced by school-going adolescents. The scale can facilitate researchers, clinicians, and teachers to identify and quantify the significant sources of stress in adolescents in school, or clinic settings.
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