Vacancy healing for stable perovskite solar cells via bifunctional potassium tartrate

Perovskite solar cell has gained widespread attention as a promising technology for renewable energy.However, their commercial viability has been hampered by their long-term stability and potential Pb leakage. Herein, we demonstrate a bifunctional passivator of the potassium tartrate(PT) to address both challenges. PT minimizes the Pb leakage in perovskites and also heals cationic vacancy defects, resulting in improved device performance and stability. Benefiting from PT modification, the power conversion efficiency(PCE) is improved to 23.26% and the Pb leakage in unencapsulated films is significantly reduced to 9.79 ppm. Furthermore, the corresponding device exhibits no significant decay in PCE after tracking at the maximum power point(MPP) for 2000 h under illumination(LED source, 100 mW cm^(-2)).

Improved interfacial adhesion for stable flexible inverted perovskite solar cells

Flexible perovskite solar cells have attracted widespread attention due to their unique advantages in lightweight,high flexibility,and easy deformation,which are suitable for portable electronics.However,the inverted(p-i-n)structured devices suffer from poor stability largely due to the low adhesion at the brittle interface(the hole transport layer/perovskite).Herein,zeolitic imidazolate framework-67(ZIF-67)is applied to inverted structured cells to optimize the interface and prolong the device lifetime.As a result,the flexible devices based on ZIF-67 obtain the champion power conversion efficiency of 20.16%.Over 1000 h under continuous light irradiation,the device retains 96%and 80%of its original efficiency without and with bias,respectively.Notably,devices show mechanical endurance with over 78%efficiency retention after 10,000 cycles of consecutive bending cycles(R=6 mm).The introduction of ZIF-67 suppresses the cracking in device bending,which results in improved environmental stability and bending durability.

Stress compensation based on interfacial nanostructures for stable perovskite solar cells

The long-term stability issue of halide perovskite solar cells hinders their commercialization.The residual stress-strain affects device stability,which is derived from the mismatched thermophysical and mechanical properties between adjacent layers.In this work,we introduced the Rb_(2)CO_(3)layer at the interface of SnO_(2)/perovskite with the hierarchy morphology of snowflake-like microislands and dendritic nanostructures.With a suitable thermal expansion coefficient,the Rb_(2)CO_(3)layer benefits the interfacial stress relaxation and results in a compressive stress-strain in the perovskite layer.Moreover,reduced nonradiative recombination losses and optimized band alignment were achieved.An enhancement of open-circuit voltage from 1.087 to 1.153 V in the resultant device was witnessed,which led to power conversion efficiency(PCE)of 22.7%(active area of 0.08313 cm^(2))and 20.6%(1 cm2).Moreover,these devices retained 95%of its initial PCE under the maximum power point tracking(MPPT)after 2700 h.It suggests inorganic materials with high thermal expansion coefficients and specific nanostructures are promising candidates to optimize interfacial mechanics,which improves the operational stability of perovskite cells.

Balancing Energy-Level Difference for Efficient n-i-p Perovskite Solar Cells with Cu Electrode

Developing low cost and stable metal electrode is crucial for mass production of perovskite solar cells(PSCs).As an earthabundant element,Cu becomes an alternative candidate to replace noble metal electrodes such as Au and Ag,due to its comparable physiochemical properties with simultaneously good stability and low cost.However,the undesirable band alignment associated with the device architecture impedes the exploration of efficient Cu-based n-i-p PSCs.Here,we demonstrated the ability of tuning the Fermi level(E_(F))of hole transport layer(HTL)to reduce the energy level difference(Schottky barrier)between HTLs and Cu.Further,we identified that the balance of energy level difference between HTL and adjacent layers(including perovskite and Cu)is crucial to efficient carrier transportation and photovoltaic performance improvement in the PSCs.Under the optimized condition,we achieve a device power conversion efficiency(PCE)of 20.10%,which is the highest on the planar n-i-p PSCs with Cu electrode.Meanwhile,the Cu-based PSCs can maintain 92%of their initial efficiency after 1000 h storage,which is comparable with Au-based devices.The present work not only extends the understanding on the band alignment of neighboring semiconductor functional layer in the device architecture to improve the resulting performance but also suggests great potential of Cu electrode for application in PSCs community.