Fabricating efficient and stable quasi-3D and 3D/2D perovskite solar cells with 2D-sheets connected by inorganic type ionic-bond

Influence of SrBr2 Doping on 4T CsPbBr3/Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3 Tandem Device for Underwater Photovoltaic Applications

Underwater photovoltaics plays a pivotal role in photovoltaic applications. However, the underwater solar spectrum differs significantly from that in air, and as water depth increases, solar spectra across various wavebands exhibit distinct attenuation rates. Specifically, the attenuation rate of the red component of sunlight is considerably higher than that of green and blue light (400-600 nm). Thus, under these unique spectral conditions, there is an urgent need to develop stable devices that minimize power conversion efficiency (PCE) loss with increasing water depth. The 4-terminal (4T) structure tandem cell, designed with 2.35 eV CsPbBr3 and 1.63 eV Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3, is prioritized due to its suitable optical response range and low PCE loss with increasing water depth. As CsPbBr3 utilized blue and green light in tandem, which has the highest light intensity underneath water, this study employed doping of SrBr2 into the CsPbBr3 film. This approach reduced the defect density of the film, enhanced carrier transport efficiency, and improved the photoelectric responsivity of the device in the 425-500 nm band. The CsPbBr3 perovskite solar cells that were fabricated demonstrated a high open-circuit voltage of 1.46 V and an exceptional PCE of 7.62%. Additionally, these devices exhibited excellent stability. Consequently, the 4T tandem device achieved PCEs of 15.28, 11.79, and 10.33% at 0, 0.5, and 0.7 m underwater depths respectively, with a variation rate of only 32%. Furthermore, the device demonstrated remarkable stability under working conditions, with an efficiency decay of less than 13% after continuous irradiation for 30 days. These findings suggest that the 4T tandem solar cell holds considerable potential for application in underwater photovoltaics.

Simultaneous passivation on both A and X sites of halogen perovskite with magnesium benzoate

Surface modification engineering is a well-known effective passivation method for making efficient and stable perovskite solar cells (PSCs). However, to our knowledge, little attention has been paid to simultaneously passivating the A and X sites of halogen perovskites. Herein, we introduced an organometallic salt (C6H5COO)2Mg (MgBEN) as a passivator, and as a result, the C6H5COOMg+ passivates the A site and C6H5COO- the X site on the perovskite layer, significantly reducing the trap-state density and nonradiative recombination. Moreover, the modification induces the perovskite film quality to improve, which may decrease the charge accumulation and facilitate carrier transport. By optimizing the concentration of the MgBEN, the perovskite film showed an increased grain size (from 1.18 μm to 1.61 μm), and the best device exhibited an enhanced power conversion efficiency (PCE) of 22.24%. Meanwhile, the device after modification performed with good long-term stability.