Suppressing the Phase Segregation with Potassium for Highly Efficient and Photostable Inverted Wide-Band Gap Halide Perovskite Solar Cells

Abstract

Wide-band gap (WBG) mixed-halide perovskites have drawn much attention because of their excellent optoelectronic properties and the potential to be deployed in tandem solar cells. Nevertheless, the bromine incorporation inevitably leads to photoinduced phase segregation in WBG mixed-halide perovskites. Herein, potassium is used to effectively suppress photoinduced phase segregation, which is visualized with confocal photoluminescence microscopy imaging. Strikingly, the potassium passivation not only inhibits the formation of the narrow-band gap subphase but also enhances the crystallinity of the WBG mixed-halide perovskite. In addition, the potassium-passivated WBG perovskite exhibits lower defect density, longer charge carrier lifetime, and better photostability. As a result, the optimized KI (2 mol %)-passivated WBG perovskite solar cells (PSCs) deliver a champion power conversion efficiency of 18.3% with negligible hysteresis. They maintain 98% of their initial efficiency after 400 h under 100 mW•cm −2 white light illumination in nitrogen.

Subtle side chain modification of triphenylamine‐based polymer hole‐transport layer materials produces efficient and stable inverted perovskite solar cells

“…Moreover, it is among the highest PCEs reported for polymer HTL-based 3D IPVSCs. [18,25,[52][53][54][55][56][57][58][59][60][61][62][63][64][65]…”

Wide‐Bandgap Organic–Inorganic Lead Halide Perovskite Solar Cells

“…[80,85] K + decorates the grain boundaries rather than being doped into the perovskite lattice, which can substantially mitigate both non-radiative recombination losses and photoinduced ion migration in perovskite films and interfaces. Liang et al deployed K + in FA 0.8 Cs 0.2 Pb(I 0.7 Br 0.3 ) 3 perovskites (E g = 1.7 eV), [85] which significantly suppressed phase segregation and reduced the voltage loss from 152 to 95 mV. Therefore, the KI-modified WBG PSCs yielded a high V OC of 1.19 V along with a PCE of 18.3%.…”

Methodologies for >30% Efficient Perovskite Solar Cells via Enhancement of Voltage and Fill Factor

“…Moreover, MA þ cation doping would reduce thermal stability due to its easy volatilization from perovskite lattices [26,83,84] and Br À doping might undergo phase segregation because of ion migration. [85][86][87] New doping ions should be developed to stabilize the α-phase while maintaining the inherent bandgap of FAPbI 3 . It was reported that methylenediammonium dichloride (MDACl 2 ) additive improved phase stability and photovoltaic performance.…”