Fully Solution Processed Pure α‐Phase Formamidinium Lead Iodide Perovskite Solar Cells for Scalable Production in Ambient Condition

Abstract

Manufacturing commercially viable perovskite solar cells still requires appropriate low‐temperature and scalable deposition processes to be developed. While α‐phase FAPbI3 has higher thermal stability and broader absorption than MAPbI3, there still is no report of a pure α‐phase FAPbI3 perovskite film obtained by a scalable printing method. Moreover, spontaneous conversion of the α‐phase to non‐perovskite δ‐phase under ambient conditions poses a serious challenge for practical applications. Herein, a scalable and fully solution based printing method for the fabrication of pure α‐phase FAPbI3 perovskite solar cells is reported. Through adding N‐methyl pyrrolidone and methylammonium chloride to the dimethylformamide based precursor solution to control the crystallization, and vacuum or air‐flow assisted film drying, pure α‐FAPbI3 phase is obtained by doctor blading. The resulting α‐FAPbI3 film is highly stable, with no δ‐FAPbI3 phase being formed even after keeping it in an ambient atmosphere over a period of 200 days without encapsulation. In addition, a fully solution processed PSC with a PCE of 16.1% is processed by the vacuum assisted method, and 17.8% by the air‐flow assisted method. Replacing silver with a printed carbon electrode provides a stable PCE up to 15% for the vacuum assisted and 16.4% for the air‐flow assisted method, which is the highest performance of FAPbI3 solar cells to date. Compared with MAPbI3, the fully printed FAPbI3 perovskite devices exhibit a remarkable thermal stability in humid atmospheres which makes them a promising candidate for scalable production and commercialization.

Development of formamidinium lead iodide-based perovskite solar cells: efficiency and stability

“…4c). 71,74 The ionic liquid can be used to stabilize α-FAPbI3 by adjusting the crystallization kinetics of the perovskite active layer. 1-hexyl-3methylimidazolium iodide ionic liquid (IL) doping is beneficial to FAPbI3 (Fig.…”

“…72 Clhas been demonstrated to improve the crystallization and reduce the non-radiative recombination of perovskites. 59,71,[75][76][77] Methylenediammonium dichloride(MDACl2) 27,28 , MACl 29 and FACl 78 has already been introduced into α-FAPbI3. MACl is considered to be a transitional "stabilizer" that does not affect the crystal structure and can induce the formation of α-FAPbI3.…”

Low Temperature Processed Fully Printed Efficient Planar Structure Carbon Electrode Perovskite Solar Cells and Modules

“…To underline the significance of this work, we first revisit the performance of fully printed PSCs with carbon-based top electrodes from previous reports and the data are summarized in Table S1, Supporting Information. [13][14][15] Figure 1a also compares the V OC and PCE versus FF of the state-of-the-art carbon electrode perovskite solar modules (carbon-PSMs). [16] It is obvious that all of the previous reports on carbon-PSMs are based on mesoporous configurations which are limited to the V OC and FF.…”

“…Recently, we have obtained PCE of 16.4% based on the printable planar n–i–p FAPbI 3 carbon‐PSCs, while the efficiency still is limited. [ 14 ] In summary, low temperature processed fully printable PSCs with affordable and stable electrodes still pose a challenge to the community.…”

Ultrathin PTAA interlayer in conjunction with azulene derivatives for the fabrication of inverted perovskite solar cells

“…The organic-inorganic hybrid perovskite solar cells (PSCs) have shown a remarkable evolution in terms of power conversion efficiency (PCE) reaching 25.2% 1 . Moreover, PSCs materials' layers are mostly deposited from solutions 2 and by techniques that are scalable for large area devices and high throughput 3,4 , thus PSCs have the potential to dominate the market either as standalone thin film solar cells 5 or in tandem solar cells with the established silicon solar cells 6,7 .…”