The mixtures of cations and anions used in hybrid halide perovskites for high-performance solar cells often undergo element and phase segregation, which limits device lifetime. We adapted Schelling’s model of segregation to study individual cation migration and found that the initial film inhomogeneity accelerates materials degradation. We fabricated perovskite films (FA
1–x
Cs
x
PbI
3
; where FA is formamidinium) through the addition of selenophene, which led to homogeneous cation distribution that retarded cation aggregation during materials processing and device operation. The resultant devices achieved enhanced efficiency and retained >91% of their initial efficiency after 3190 hours at the maximum power point under 1 sun illumination. We also observe prolonged operational lifetime in devices with initially homogeneous FACsPb(Br
0.13
I
0.87
)
3
absorbers.
Formamidinium (FA)-based lead triiodide have emerged as promising light-harvesting materials for solar cells due to their intriguing optoelectronic properties. However, obstacles to commercialization remain regarding the primary intrinsic materials instability, wherein volatile organic components of FA + cations are prone to escape under operational stressors. Herein, stabilizing FA-based perovskite through toughening the interface with the symmetric molecule of 1,1′-(Methylenedi-4,1-phenylene) bismaleimide (BMI) is reported. BMI with two maleimides can simultaneously bind with FA + and/or undercoordinated Pb 2+ through chemical bonding, which also compresses the resultant perovskite lattice. The chemical bonding and strain modulation synergistically not only passivate film defects, but also inhibit perovskite decomposition, thus significantly improving the intrinsic stability of perovskite films. As a result, the BMI-modified perovskite solar cells (PSCs) show improved power conversion efficiency (PCE) from 21.4% to 22.7% and enhanced long-term operational stability, maintaining 91.8% of the initial efficiency after 1000 h under continuous maximum power point tracking. The findings shed light on the synergetic effects of chemical interactions and physical regulations, which opens a new avenue for stable and efficient perovskite-based optoelectronic devices.
Perovskite/silicon tandem solar cells are promising to penetrate photovoltaic market. However, the wide‐bandgap perovskite absorbers used in top‐cell often suffer severe phase segregation under illumination, which restricts the operation lifetime of tandem solar cells. Here, a strain modulation strategy to fabricate light‐stable perovskite/silicon tandem solar cells is reported. By employing adenosine triphosphate, the residual tensile strain in the wide‐bandgap perovskite absorber is successfully converted to compressive strain, which mitigates light‐induced ion migration and phase segregation. Based on the wide‐bandgap perovskite with compressive strain, single‐junction solar cells with the n–i–p layout yield a power conversion efficiency (PCE) of 20.53% with the smallest voltage deficits of 440 mV. These cells also maintain 83.60% of initial PCE after 2500 h operation at the maximum power point. Finally, these top cells are integrated with silicon bottom cells in a monolithic tandem device, which achieves a PCE of 26.95% and improved light stability at open‐circuit.
Metal halide perovskites are promising as next‐generation photovoltaic materials, but stability issues are still a huge obstacle to their commercialization. Here, the formation and evolution of cracks in perovskite films during thermal cycling, which affect their mechanical stability, are investigated. Compressive strain is employed to suppress cracks and delamination by in situ formed polymers with low elastic modulus during crystal growth. The resultant devices pass the thermal‐cycling qualification (IEC61215:2016), retaining 95% of the initial power conversion efficiency (PCE) and compressive strain after 230 cycles. Meanwhile, the p–i–n devices deliver PCEs of 23.91% (0.0805 cm2) and 23.27% (1 cm2). The findings shed light on strain engineering with respect to their evolution, which enables mechanically stable perovskite solar cells.
Perovskite solar cells (PSCs) have achieved great development
since
2009 because of their unique optoelectronic properties. However, the
critical challenges in perovskite photovoltaics still hinder their
practical application. The performance of PSCs is governed by a number
of indivisible factors during device fabrication, some of which are
implicit and receive little attention. Conventional research often
follows an iterative trial and error manner to optimize the PSCs,
wherein the underlying mechanisms for major processing are not clear.
Bayesian Optimization (BO) shows great potential for accelerating
the development of processing chemistry for PSCs, which have received
success in resolving the black-box problems in artificial intelligence
(AI). In this Perspective, we briefly introduce the BO algorithm and
review and discuss the applications of BO in the field of perovskite
photovoltaics. Outlooks of the BO applications in processing chemistry
of PSCs are proposed briefly.
Possessed with advantageous optoelectronic properties, perovskites have boosted the rapid development of solution-processed solar cells. The performance of perovskite solar cells (PSCs) is significantly weakened by the carrier loss at grain boundary grooves (GBGs); however, it receives limited attention and there lacks effective approach to solve this issue. Herein, for the first time, we constructed the tungstate/perovskite heterointerface via a "two step" in situ reaction approach that provides effective defect passivation and ensures efficient carrier dynamics at the GBGs. The exposed perovskite at grain boundaries is converted to wideband-gap PbWO 4 via an in-situ reaction between Pb 2 + and tungstate ions, which passivate defects due to the strong ionic bonding. Moreover, recombination loss is further suppressed via the heterointerface energetics modification based on an additional transformation from PbWO 4 to CaWO 4 . PSCs based on this groove modification strategy showed good universality in both normal and inverted structure, with an improved efficiency of 23.25 % in the n-i-p device and 23.33 % in the p-i-n device. Stable power output of the modified device could maintain 91.7 % after around 1100 h, and the device efficiency could retain 92.5 % after aging in air for around 2110 h, and 93.1 % after aging at 85 °C in N 2 for 972 h.
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