Improving the Quality of CsPbBr₃ Films by Applying the Light Soak

Abstract

A technique for improving the quality of CsPbBr3 films by combing the annealing and the light soak is proposed and experimentally demonstrated. Well-organized CsPbBr3-based solar cells with an optimized power conversion efficiency of about 8.6% are obtained. The efficiency is improved by about 28% compared to that of the solar cells based on the films treated only by the post-annealing process. The light-soak effects on the improvement of CsPbBr3 films may open a route in fabricating high-quality film solar cells.

Passivation Effect of CsPbBr3 Films Based on SnBr4 Post-Treatment

“…However, the intensity has significantly increased in modified samples, indicating the inhibition of nonradiative recombination. These findings are consistent with previous research. − The carrier lifetime can be derived from the decay curves of photoluminescence intensity using a biexponential decay equation: I ( t ) = I 0 + A 1 exp­(− t /τ 1 ) + A 2 exp­(− t /τ 2 ), where τ 1 and τ 2 correspond to fast decay time constants and slow decay time constants, respectively. , The average carrier lifetime (τ avg ) can be calculated as τ avg = (A 1 τ 1 2 + A 2 τ 2 2 )/(A 1 τ 1 + A 2 τ 2 ). For the TRPL measurements, the PL lifetimes of modified perovskite films are consistently longer than those of the control sample (Table ).…”

“…The results are shown in Figure c. The trap-state density ( N trap ) can be calculated using the equation: N trap = (2 V TFL εε 0 )/( eL 2 ), where the dielectric constant is represented by ε, ε 0 denotes the vacuum permittivity, e is the charge of an electron, and L is the thickness of the film. , V TFL is obtained through data fitting. The calculated value of N trap decreases from 3.42 × 10 16 cm 3 for the control sample to 3.07 × 10 16 cm 3 for the modified sample.…”

“…41−43 The carrier lifetime can be derived from the decay curves of photoluminescence intensity using a biexponential decay equation: I(t) = I 0 + A 1 exp(−t/τ 1 ) + A 2 exp(−t/τ 2 ), where τ 1 and τ 2 correspond to fast decay time constants and slow decay time constants, respectively. 23,29 The average carrier lifetime (τ avg ) can be calculated as…”

“…Although the variation is minor, the adjusted E VB and W F of the CsPbBr 3 film provide a more appropriate energy-level arrangement, promoting the balance of electron and hole separation. 29,44 The gradient level alignment introduced by SnBr 4 plays a positive role in facilitating hole extraction and is favorable for V OC improvement. 45 During the measurements of PSCs, we observed a pervasive issue known as hysteresis, which is characterized by variations in the shapes of J−V characteristics based on the scanning direction and rate.…”

“…The performance of PSCs is mainly affected by two factors: nonradiative recombination activated by surface defects and the carrier extraction determined by the energy level arrangement. − In order to reduce the defects of CsPbBr 3 films, various preparation and passivation methods have been developed. For example, methods such as continuous spin-coating, immersion, and infiltration spin-coating have been sequentially developed to obtain CsPbBr 3 films with pure phases and to minimize the effect of impurity phases on the optoelectronic properties. ,, Additive engineering using NH 4 SCN, SnBr 2 , BiBr 3 , acetic acid, 2-Guanidinoacetic acid, a light soaking-assisted method, and a solvent-controlled growth strategy have been developed to efficiently passivate defects by regulating crystallization kinetics. − Inorganic PSCs without a hole transport layer often experience significant energy level mismatches. To address this issue, researchers have optimized the carrier extraction process of CsPbBr 3 PSCs by using interfacial layers, such as MnS .…”