Solvent-Free Method for Defect Reduction and Improved Performance of p-i-n Vapor-Deposited Perovskite Solar Cells

Abstract

As perovskite-based photovoltaics near commercialization, it is imperative to develop industrial-scale defect-passivation techniques. Vapor deposition is a solvent-free fabrication technique that is widely implemented in industry and can be used to fabricate metal-halide perovskite thin films. We demonstrate markably improved growth and optoelectronic properties for vapor-deposited [CH(NH 2 ) 2 ] 0.83 Cs 0.17 PbI 3 perovskite solar cells by partially substituting PbI 2 for PbCl 2 as the inorganic precursor. We find the partial substitution of PbI 2 for PbCl 2 enhances photoluminescence lifetimes from 5.6 ns to over 100 ns, photoluminescence quantum yields by more than an order of magnitude, and charge-carrier mobility from 46 cm 2 /(V s) to 56 cm 2 /(V s). This results in improved solar-cell power conversion efficiency, from 16.4% to 19.3% for the devices employing perovskite films deposited with 20% substitution of PbI 2 for PbCl 2 . Our method presents a scalable, dry, and solvent-free route to reducing nonradiative recombination centers and hence improving the performance of vapor-deposited metal-halide perovskite solar cells.

Thermally Stable Perovskite Solar Cells by All-Vacuum Deposition

“…The strongly increasing optical absorption coefficient of FA 0.83 Cs 0.17 PbI 3 as the wavelength is reduced results in the bluer light generating electron−hole pairs very close to the HTL interface in solar cells with a p−i−n architecture. 22 This means holes are more readily extracted due to the short distance to the electrode, whereas electrons have to traverse most of the device depth. The drop in EQE at wavelength <500 nm for solar cells with ZnPc HTLs as compared against those with CuPc HTLs indicates that electrons recombine rapidly at the FA 0.83 Cs 0.17 PbI 3 −ZnPc interface or are extracted into the ZnPc and recombine there.…”

“…The strongly increasing optical absorption coefficient of FA 0.83 Cs 0.17 PbI 3 as the wavelength is reduced results in the bluer light generating electron–hole pairs very close to the HTL interface in solar cells with a p–i–n architecture . This means holes are more readily extracted due to the short distance to the electrode, whereas electrons have to traverse most of the device depth.…”

“…24 materials. 20,22,25,26 Not only are these aforementioned HTLs relatively expensive, 27 but the additional solution-processing step also adds complication to the overall fabrication process, and thus could impede commercialization and large-scale production. Furthermore, materials such as Spiro-OMeTAD and PTAA are prone to degradation under environmental stressors such as temperature and humidity, thus curtailing the operational lifetimes of PSCs when incorporated into the device structure.…”

2D Material and Perovskite Heterostructure for Optoelectronic Applications

“…To solve this problem, vapor-deposited MA-free perovskite films have been studied. For instance, Lohmann and coworkers showed that partially substituting PbCl 2 for PbI 2 could significantly suppress defects in FA 0.83 Cs 0.17 PbI 3 films [82].…”

Tautomeric Passivation Strategy-Assisted Photostable Perovskite Solar Modules

“…Organic–inorganic halide perovskite solar cells (PSCs) have drawn considerable attention over the past decade because of the remarkable certified power conversion efficiency (PCE) up to 25% for small-area devices. − Despite the attractive PCE in small-area devices, the long-term stability of perovskite solar modules (PSMs) still presents many challenges, which are mainly affected by oxygen, moisture, heat, and high-energy irradiation. − Thus, the literature reports decelerating the degradation of the perovskite and prolonging the PSC lifetime via the methods of hydrophobic treatment, interfacial modification, and encapsulation. , However, the photostability of the PSMs (especially under UV irradiation), as a nonnegligible point in the practical application process, has rarely been reported. In particular, the strong UV light in the solar spectrum easily destroys the perovskite materials, inducing undesirable vacancies , (V MA or FA , V Pb , and V I ), ion migration, and halide segregation. ,,, Meanwhile, the inevitable defects in the process of large-scale perovskite film fabrication − further aggravate the photodegradation of the organic ions (FA + /MA + ) in the PSM.…”