A Versatile Molten‐Salt Induction Strategy to Achieve Efficient CsPbI₃ Perovskite Solar Cells with a High Open‐Circuit Voltage >1.2 V

Abstract

All‐inorganic CsPbI3 perovskite has emerged as an important photovoltaic material due to its high thermal stability and suitable bandgap for tandem devices. Currently, the cell performance of CsPbI3 solar cells is mainly subject to a large open‐circuit voltage (VOC) deficit. Herein, a multifunctional room‐temperature molten salt, dimethylamine acetate (DMAAc) is demonstrated, which not only directly acts as a solvent for precursor solutions, but also regulates the phase conversion process of the CsPbI3 film for high‐efficiency photovoltaics. DMAAc can stabilize the DMAPbI3 structure and eliminate the Cs4PbI6 intermediate phase, which is easily spatially segregated. Meanwhile, a new homogeneous intermediate phase DMAPb(I,Ac)3 is formed, which finally affords high‐quality CsPbI3 films. With this approach, the charge capture activity of defects in the CsPbI3 film is significantly suppressed. Consequently, a VOC of 1.25 V and >21% power conversion efficiency are achieved, which is the record highest reported thus far. This intermediate phase‐regulation strategy is believed to be applicable to other perovskite material systems.

Surface Sn(IV) Hydrolysis Improves Inorganic Sn–Pb Perovskite Solar Cells

“…More impressively, the champion SSH-Cl device exhibits PCEs of 16.79% and 15.39% for the reverse and forward scans, respectively, and the SPO yields a PCE of 16.14%. This is the highest PCE so far in the device category of inorganic Sn–Pb PSCs (Figure S14 ,,,− ). The external quantum efficiency (EQE) spectrum of the champion SSH-Cl device (Figure f) is in agreement with the J SC value in Figure d by virtue of its integrated J SC (24.57 mA cm –2 ) over the measured wavelength range.…”

Monovalent Copper Cation Doping Enables High-Performance CsPbIBr2-Based All-Inorganic Perovskite Solar Cells

“…For instance, the PCEs of CsPbI 3 -based PSCs with a proper band gap of 1.73 eV have reached 21% nowadays. However, CsPbI 3 perovskites suffer from the detrimental phase transformation from black CsPbI 3 non-perovskite yellow phase with a much wider band gap (3.01 eV) at room temperature, exhibiting negative impacts on the PCEs and the stability of CsPbI 3 -based PSCs [ 42 , 43 ]. In contrast, CsPbBr 3 perovskites have exhibited excellent phase structural stability and high heat/moisture tolerance, which suffered from the extremely large band gap (2.3 eV), remarkably limiting sunlight absorption range and then the cell performance [ 44 , 45 ].…”

Constructing a Surface Multi-cationic Heterojunction for CsPbI1.5Br1.5 Perovskite Solar Cells with Efficiency beyond 14%

“…In addition, the efficient CsPbI 2 Br PSCs have also been achieved with the PCE of 17.46% . Unfortunately, the humidity-induced phase instability of both CsPbI 3 and CsPbI 2 Br PSCs still impedes further development. − Most recently, an outstanding record efficiency of 12.05% for CsPbIBr 2 PSCs was achieved by Duan et al via proposing a dynamic healing interface (DHI) . For all of this, CsPbIBr 2 PSCs are still inefficient compared to their peers mainly as a result of the serious optical loss. − …”