No abstract

Organic–inorganic lead halide perovskites (OIHPs) have emerged as promising materials for next‐generation photovoltaics. However, performance improvements in the perovskite‐based device are still limited due to defects that exist more intensively on the surface as well as grain boundaries (GBs) and mismatching energy levels at the interface. Herein, a reactive post‐treatment process (RPP) using guanidine acetate (GA) is adopted to address defects and interfacial energy level matching at the perovskite surface. The RPP with GA (GA‐RPP) results in the formation of an improved perovskite layer with large grain size and low GB density, leading to the formation of secondary phases on the perovskite surface with appropriate energy levels, resulting in reduced defect density and charge recombination. Furthermore, density functional theory analysis reveals that the Pb‐rich secondary phase could improve the conduction of electrons at the perovskite interface. Therefore, the GA‐RPP‐based perovskite‐based solar cell (PSC) shows enhanced performance with 20.4% efficiency and long‐term stability.

No abstract

No abstract

No abstract

No abstract

No abstract

LiNiO 2 , LiNi 0.995 Al 0.005 O 2 , LiNi 0.975 Ga 0.025 O 2 , LiNi 0.990 Ti 0.010 O 2 and LiNi 0.990 Al 0.005 Ti 0.005 O 2 were synthesized by preheating at 400°C for 30 min in air and calcination at 750°C for 36 h in an O 2 stream with excess lithium amount z = 0.10 in Li 1?z Ni 1-y M y O 2 . For these samples, the discharge capacities and discharge capacity degradation rate are compared. LiNiO 2 has the largest discharge capacity at the 20th cycle (n = 20) and the 50th cycle (n = 50). LiNiO 2 and LiNi 0.995 Al 0.005 O 2 have relatively good cycling performances and their discharge capacities at n = 50 are 134 and 123 mAh/g, respectively, at 0.1 C rate. The crystallite sizes and strains were calculated by the Williamson-Hall method with XRD patterns and compared for the samples as prepared and after 50 charge-discharge cycles.