Perovskite solar cells (PSCs) have shown great promise for photovoltaic applications, owing to their low‐cost assembly, exceptional performance, and low‐temperature solution processing. However, the advancement of PSCs towards commercialization requires improvements in efficiency and long‐term stability. The surface and grain boundaries of perovskite layer, as well as interfaces, are critical factors in determining the performance of the assembled cells. Defects, which are mainly located at perovskite surfaces, can trigger hysteresis, carrier recombination, and degradation, which diminish the power conversion efficiencies (PCEs) of the resultant cells. This study concerns the stabilization of the α‐FAPbI3 perovskite phase without negatively affecting the spectral features by using 2,3,4,5,6‐pentafluorobenzyl phosphonic acid (PFBPA) as a passivation agent. Accordingly, high‐quality PSCs are attained with an improved PCE of 22.25 % and respectable cell parameters compared to the pristine cells without the passivation layer. The thin PFBPA passivation layer effectively protects the perovskite layer from moisture, resulting in better long‐term stability for unsealed PSCs, which maintain >90 % of the original efficiency under different humidity levels (40–75 %) after 600 h. PFBPA passivation is found to have a considerable impact in obtaining high‐quality and stable FAPbI3 films to benefit both the efficiency and the stability of PSCs.
Defect
states at surfaces and grain boundaries as well as poor
anchoring of perovskite grains hinder the charge transport ability
by acting as nonradiative recombination centers, thus resulting in
undesirable phenomena such as low efficiency, poor stability, and
hysteresis in perovskite solar cells (PSCs). Herein, a linear dicarboxylic
acid-based passivation molecule, namely, glutaric acid (GA), is introduced
by a facile antisolvent additive engineering (AAE) strategy to concurrently
improve the efficiency and long-term stability of the ensuing PSCs.
Thanks to the two-sided carboxyl (−COOH) groups, the strong
interactions between GA and under-coordinated Pb2+ sites
induce the crystal growth, improve the electronic properties, and
minimize the charge recombination. Ultimately, champion-stabilized
efficiency approaching 22% is achieved with negligible hysteresis
for GA-assisted devices. In addition to the enhanced moisture stability
of the devices, considerable operational stability is achieved after
2400 h of aging under continuous illumination at maximum power point
(MPP) tracking.
Despite the outstanding role of mesoscopic structures on the efficiency and stability of perovskite solar cells (PSCs) in the regular (n–i–p) architecture, mesoscopic PSCs in inverted (p–i–n) architecture have rarely been reported. Herein, an efficient and stable mesoscopic NiOx (mp‐NiOx) scaffold formed via a simple and low‐cost triblock copolymer template‐assisted strategy is employed, and this mp‐NiOx film is utilized as a hole transport layer (HTL) in PSCs, for the first time. Promisingly, this approach allows the fabrication of homogenous, crack‐free, and robust 150 nm thick mp‐NiOx HTLs through a facile chemical approach. Such a high‐quality templated mp‐NiOx structure promotes the growth of the perovskite film yielding better surface coverage and enlarged grains. These desired structural and morphological features effectively translate into improved charge extraction, accelerated charge transportation, and suppressed trap‐assisted recombination. Ultimately, a considerable efficiency of 20.2% is achieved with negligible hysteresis which is among the highest efficiencies for mp‐NiOx based inverted PSCs so far. Moreover, mesoscopic devices indicate higher long‐term stability under ambient conditions compared to planar devices. Overall, these results may set new benchmarks in terms of performance for mesoscopic inverted PSCs employing templated mp‐NiOx films as highly efficient, stable, and easy fabricated HTLs.
The regular architecture (n-i-p) of perovskite solar
cells (PSCs)
has attracted increasing interest in the renewable energy field, owing
to high certified efficiencies in the recent years. However, there
are still serious obstacles of PSCs associated with spiro-OMeTAD hole
transport material (HTM), such as (i) prohibitively expensive material
cost (∼150–500 $/g) and (ii) operational instability
at elevated temperatures and high humidity levels. Herein, we have
reported the highly photo, thermal, and moisture-stable and cost-effective
PSCs employing inorganic CuFeO2 delafossite nanoparticles
as a HTM layer, for the first time. By exhibiting superior hole mobility
and additive-free nature, the best-performing cell achieved a power
conversion efficiency (PCE) of 15.6% with a negligible hysteresis.
Despite exhibiting a lower PCE as compared to the spiro-OMeTAD-based
control cell (19.1%), nonencapsulated CuFeO2-based cells
maintained above 85% of their initial efficiency, while the PCE of
control cells dropped to ∼10% under continuous illumination
at maximum power point tracking after 1000 h. More importantly, the
performance of control cells was quickly degraded at above 70 °C,
whereas CuFeO2-based cells, retaining ∼80% of their
initial efficiency after 200 h, were highly stable even at 85 °C
in ambient air under dark conditions. Besides showing significant
improvement in stability against light soaking and thermal stress,
CuFeO2-based cells exhibited superior shelf stability even
at 80 ± 5% relative humidity and retained over 90% of their initial
PCE. Overall, we strongly believe that this study highlights the potential
of inorganic HTMs for the commercial deployment of long-term stable
and low-cost PSCs.
Despite the impressive efficiency of perovskite solar cells (PSCs), their operational stability is still hindered by the thermodynamic instability of the hybrid organic-inorganic absorber layer with ABX3 structure (A: organic/inorganic...
Electron transporting layer (ETL)-free perovskite solar
cells (PSCs)
exhibit promising progress in photovoltaic devices due to the elimination
of the complex and energy-/time-consuming preparation route of ETLs.
However, the performance of ETL-free devices still lags behind conventional
devices because of mismatched energy levels and undesired interfacial
charge recombination. In this study, we introduce sodium fluoride
(NaF) as an interface layer in ETL-free PSCs to align the energy level
between the perovskite and the FTO electrode. KPFM measurements clearly
show that the NaF layer covers the surface of rough underlying FTO
very well. This interface modification reduces the work function of
FTO by forming an interfacial dipole layer, leading to band bending
at the FTO/perovskite interface, which facilitates an effective electron
carrier collection. Besides, the part of Na+ ions is found
to be able to migrate into the absorber layer, facilitating enlarged
grains and spontaneous passivation of the perovskite layer. As a result,
the efficiency of the NaF-treated cell reaches 20%, comparable to
those of state-of-the-art ETL-based cells. Moreover, this strategy
effectively enhances the operational stability of devices by preserving
94% of the initial efficiency after storage for 500 h under continuous
light soaking at 55 °C. Overall, these improvements in photovoltaic
properties are clear indicators of enhanced interface passivation
by NaF-based interface engineering.
We tried to demonstrate the implications of employing different TiO2 templated films as blocking layers for improving the input light transmittance and efficiency of dye sensitized and perovskite solar cells.
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