Intermediate-Phase-Modified Crystallization for Stable and Efficient CsPbI₃ Perovskite Solar Cells

Abstract

All-inorganic CsPbI3 perovskite solar cells (PSCs) are becoming desirable for their excellent photovoltaic ability and adjustable crystal structure distortion. However, the unsatisfactory crystallization of the perovskite phase is unavoidable and leads to challenges on the road to the development of high-quality CsPbI3 perovskite films. Here, we reported the intermediate-phase-modified crystallization (IPMC) method, which introduces pyrrolidine hydroiodide (PI) before the formation of the perovskite phase. The hydrogen bonding, which originates from the interaction between the −NH in PI and the dimethylammonium iodide (DMAI) from the precursor solution, improved the crystallization conditions and further prompted the transition from the DMAPbI3 phase to CsPbI3 perovskite phase. The application of the IPMC method not only decreased the trap density but also changed the energy alignment for better separation of electron–hole pairs. As a result, the devices based on the PI-CsPbI3 perovskite films reached an efficiency of 18.72% and maintained 85% of their initial PCE after 1000 h of being stored in an ambient environment (∼25% RH, 25 °C). This work stimulates inspiration on how to conveniently fabricate high-quality perovskite films in industry.

Clothing CsPbI3 perovskite in a robust phase-pure armor to boost the thermal stability

“…The trap state density ( N t ) was calculated by V TFL using eqn (3): V TFL = eN t L 2 / 2 ε r ε 0 where e is the elementary charge, N t is the trap state density, L is the film thickness, ε 0 is the vacuum permittivity, and ε r is the relative permittivity of CsPbI 3 . 43 As expected, the IT1.5-CsPbI 3 film exhibited a lower trap state density ( N t = 1.016 × 10 15 cm −3 ) than the pristine CsPbI 3 film ( N t = 1.680 × 10 15 cm −3 ), well-confirming the reduced defects.…”

“…where e is the elementary charge, N t is the trap state density, L is the lm thickness, 3 0 is the vacuum permittivity, and 3 r is the relative permittivity of CsPbI 3 . 43 As expected, the IT1.5-CsPbI 3 lm exhibited a lower trap state density (N t = 1.016 × 10 15 cm −3 ) than the pristine CsPbI 3 lm (N t = 1.680 × 10 15 cm −3 ), well-conrming the reduced defects. CsPbI 3 C-PSCs with the architecture of FTO/compact TiO 2 / meso-TiO 2 /CsPbI 3 /carbon were fabricated by directly painting commercial carbon paste on the perovskite lms, followed by annealing at 100 °C.…”

In Situ Growth of a Robust 1D Capping Layer for Stable and Efficient CsPbI3 Perovskite Solar Cells Without Hole Transporter

“…where 𝜖 0 is the vacuum permittivity, 𝜖 is the relative permittivity of CsPbI 3 perovskite, L is the thickness of the perovskite films, e is the basic charge. [55] The CsPbI 3 device exhibits a V TFL of 1.14 V, which is reduced to 0.87 V for the CsPbI 3 /ASNPbI 3 device, corresponding to the reduction of the N t from 4.80 × 10 15 cm −3 to 3.66 × 10 15 cm −3 . Therefore, the SCLC results further confirm that the formation of the ASNPbI 3 layer has well suppressed the generation of crystal defects for lowering trap state density in CsPbI 3 perovskite.…”

“…The trap state density ( N t ) can be calculated by the trap‐filled limit voltage ( V TFL ) using Equation (3): $$$$\begin{equation}{V}_{{\mathrm{TFL}}} = \left( {e{L}^2{N}_t} \right)/\left( {2{\varepsilon }_0\varepsilon } \right)\end{equation}$$$$where ε 0 is the vacuum permittivity, ε is the relative permittivity of CsPbI 3 perovskite, L is the thickness of the perovskite films, e is the basic charge. [ 55 ] The CsPbI 3 device exhibits a V TFL of 1.14 V, which is reduced to 0.87 V for the CsPbI 3 /ASNPbI 3 device, corresponding to the reduction of the N t from 4.80 × 10 15 cm −3 to 3.66 × 10 15 cm −3 . Therefore, the SCLC results further confirm that the formation of the ASNPbI 3 layer has well suppressed the generation of crystal defects for lowering trap state density in CsPbI 3 perovskite.…”

Efficient and Stable β-CsPbI3Solar Cells through Solvent Engineering with Methylamine Acetate Ionic Liquid

“…Recently, the performance of inorganic perovskite solar cells has developed rapidly due to the fabrication of a high-quality CsPbI 3 film and the stabilization of its photoactive black phase. Researchers have been working on a variety of strategies to improve the performance of the black-phase CsPbI 3 , including additive engineering, − constituent engineering, − and organic cation surface engineering, − by introducing long-chain amine cations, polymers, and polar organic molecules into the CsPbI 3 precursor solution to passivate defects, improve film quality, and stabilize the photoactive phase of CsPbI 3 . These strategies have promoted the stability and PCE of CsPbI 3 -based devices.…”