Crystallization Kinetics Control Enabled by a Green Ionic Liquid Additive toward Efficient and Stable Carbon-Based Mesoscopic Perovskite Solar Cells

Abstract

Carbon-based mesoscopic perovskite solar cells (MPSCs) are becoming one of the most competitive photovoltaic technologies owing to their lower manufacturing cost and excellent stability. In this work, methylammonium acetate (MAAc), an ionic liquid additive, is added into methylammonium lead triiodide (MAPbI 3 ) perovskite and is used to fabricate high-performance MPSCs. Systematic and detailed studies have shown that the MAAc interacts with PbI 2 preferentially to form a MAPbI 3−x (Ac) x intermediate phase that can effectively control the crystallization kinetics of MAPbI 3 in the triple-mesoscopic layer. MAPbI 3 films with an appropriate amount of MAAc exhibit higher crystallinity, lower defect density, and dense pore filling, which effectively reduce carrier nonradiative recombination loss in MPSCs. As a result, a champion power conversion efficiency (PCE) of 13.54% is obtained based on the optimized MAAc-engineered MPSCs. The PCE is 24% higher than 10.90% of the control devices. Moreover, unencapsulated MAAc-engineered MPSCs retain 90% of their initial PCE after being stored in the dark for 50 days under ambient atmosphere, which demonstrates much better air stability than control devices. This work provides an effective strategy for developing efficient and stable carbon-based MPSCs with an eco-friendly ionic liquid additive.

Efficient and stable full-printed mesoscopic perovskite solar cells with potassium hexafluorophosphate additives

“…Since the FTO substrate is conductive, the carrier lifetime characterizes the charge extraction rate. 39,41 Thus, the short s ave means the charge transport efficiency is enhanced by the KPF 6 additive. The above improvement can be attributed to the coordination between PF 6 − and uncoordinated Pb 2+ and the passivation of ionic defects in the grain boundaries by K + ions, thus improving the lm quality, suppressing nonradiative complexation, and accelerating the charge extraction rate.…”

Comprehensively Improved the Performance of Carbon‐Based Printed Mesoscopic (FA)CsRbPbI3 Solar Cells by 3‐Pyridine Formamide

“…[26,27] The reasons for the shift of the aforementioned characteristic peaks are that the NTM acts as a Lewis base and can provide electron pairs for the free Pb 2þ in the perovskites, thus the electron cloud density outside the nucleus of Pb 2þ increases after the introduction of NTM, causing a shift in binding energy to lower energy levels. [28] Alternatively, the decrease in I À binding energy may be due to the formation of N─H…I hydrogen bonds within the perovskites and the reduced interaction between I À and Pb 2þ after the introduction of NTM. [28,29] The full spectrum is shown in Figure S1(XPS), and S2(FTIR), Supporting Information.…”

“…[28] Alternatively, the decrease in I À binding energy may be due to the formation of N─H…I hydrogen bonds within the perovskites and the reduced interaction between I À and Pb 2þ after the introduction of NTM. [28,29] The full spectrum is shown in Figure S1(XPS), and S2(FTIR), Supporting Information.…”

Two Birds with One Stone: Defect Passivation and Energy Level Optimization Achieved by Using Ionic Liquid Additives for Printable Mesoscopic Perovskite Solar Cells with Efficiency beyond 16%

“…Ionic liquid 1-ethylpyridine chloride (1-EC) was applied as an additive in p-MPSCs to promote the rapid nucleation of perovskites in p-MPSCs . Wang et al used methylammonium acetate (MAAc) as an ionic liquid additive in methylammonium triiodide (MAPbI 3 ) calcium titanite, achieving improved crystalline quality and stoma filling of the perovskites, with the MAPbI 3‑x (Ac) x intermediate phase formed by the interaction of MAAc and PbI 2 .…”

“…Ionic liquid 1-ethylpyridine chloride (1-EC) was applied as an additive in p-MPSCs to promote the rapid nucleation of perovskites in p-MPSCs. 22 Wang et al 23 In this study, 1-benzyl-3-methylimidazolium chloride (BZMIMCl) ionic liquid was introduced as an imidazolium additive in p-MPSCs for the first time. The addition of BZMIMCl effectively passivated the uncoordinated Pb 2+ , improved the crystalline quality of perovskite films, and optimized the energy level alignment between the perovskites and carbon electrodes, thereby improving the built-in electric field (BEF) and promoting carrier transport.…”