Synergistic Effect of Defect Passivation and Crystallization Control Enabled by Bifunctional Additives for Carbon-Based Mesoscopic Perovskite Solar Cells

Abstract

The emerging carbon-based mesoscopic perovskite solar cells (MPSCs) are known as one of the most promising candidates for photovoltaic applications thanks to their screen-printing process and excellent stability. Unfortunately, they usually suffer from serious defects because it is challenging to realize sufficient mesopore filling of the perovskite precursor solution throughout the triple-mesoporous scaffold. Herein, a bifunctional additive, biuret, endowed with both carbonyl and amino groups, was designed to realize a convenient fabrication approach for controllable crystallization of the precursor solution. Owing to the strong coordination ability with perovskite components, the incorporation of biuret can not only regulate crystallization kinetics allowing for the growth of high-quality perovskite crystals but also associate with uncoordinated ions for defect passivation to enhance the overall photovoltaic performance of MPSCs. A champion power conversion efficiency (PCE) of 13.42% with an enhanced short-circuit current density of 19.49 mA cm −2 and a much higher open-circuit voltage of 0.96 V was achieved for the device doped with 3 mol % biuret, which is 26% higher than that of the control device (10.66%). Moreover, the unencapsulated devices with biuret incorporation demonstrated superior stability, maintaining over 90% of the original PCE after 50 days of storage under ambient conditions. This work helps exploit bifunctional additive strategies for simultaneous defect passivation and crystallization control toward high-efficiency and long-term stability of carbon-based MPSCs.

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

“…36 TRPL decay measurements were adopted to further study the carrier lifetime within the different perovskite films and the charge extraction at the interface between TiO 2 ETL and perovskite films. 35 TRPL decay was fitted using the following biexponential decay equation (eq 1), and average lifetime (τ ave ) was calculated in accordance with eq 2; the corresponding results are shown in Table S1:…”

“…31−34 Although carbon-based MPSCs have many advantages, they present a relatively low current density (J SC ) and fill factor (FF) due to the difficulty of filling sufficient and uniform perovskite precursor solution into the three-layer mesoscopic architecture, resulting in the device performance of carbon-based MPSCs being still inferior to that of planarstructure PSCs. 35,36 The facile one-step drop-coating method involves an uncontrollable crystallization process due to the limitation of micron-thick triple-mesoscopic layers, which is different from the anti-solvent and sequential deposition techniques. 37,38 Therefore, the key scientific issue is to effectively regulate the crystallization and crystal growth of halide perovskites, which is expected to reduce the probability of carrier non-radiative recombination in actual operations, thereby producing high-performance devices.…”

A synergistic co-passivation strategy for high-performance perovskite solar cells with large open circuit voltage

“…3a). 40,41 The higher the absorption intensity, larger short circuit current density (J sc ) may be obtained. The UV-vis absorption spectra of CFM treated only with M-QDs or OAI are also obtained as shown in Fig.…”

Ways to Improve the Performance of Triple‐Mesoscopic Hole‐Conductor‐Free Perovskite‐Based Solar Cells

“…Reproduced with permission. [ 65 ] Copyright 2021, American Chemical Society. b) The 4‐(aminomethyl) benzoic acid hydroiodide (AB) molecule.…”

“…[62][63][64] The addition of these AB organic molecules to the perovskite precursor solution creates nucleation seeds inside the solution, which permit further growth. In addition to the report on AB as a possible bifunctional molecule, Dongjie Wang et al [65] used the biuret molecule as a bifunctional agent. The structure of the biuret and the AB molecules can be found in Figure 6a,b, respectively.…”