δ‐Phase Management of FAPbBr₃ for Semitransparent Solar Cells

Abstract

ST-SCs due to proper band gap and stability. [4] However, the low PCE of FAPbBr 3 solar cells (SCs) seriously hinders their applications. Thus, many efforts have been made to improve the PCE of FAPbBr 3 SCs by additive engineering, [5] interface engineering, [6] and crystallization regulation. [7] For example, Ko et al. added cesium bromide to regulate lattice interactions of FAPbBr 3 with preferred orientation and obtained 8.56% of a PCE due to the highquality crystalline film. [8] Zhang et al. introduced guanidinium bromide to modulate the crystallization process, achieving a PCE of 8.92% with an open-circuit voltage (Voc) of 1.639 V for FAPbBr 3 SCs. [9] Liu et al. constructed 2D/3D perovskite interface by phenethylammonium bromide, which significantly passivated the interface defects and improved the PCE from 7.7% to 9.4%. [10] Although the PCE of FAPbBr 3 SCs has been improved, it is still unclear and rarely investigated on the effect of δ phase (δ-FAPbBr 3 ) on film and device properties. The photoinactive δ-FAPbBr 3 has a large band gap and chain structure, which may affect light absorption and carrier transport. [11] Therefore, the research on δ-FAPbBr 3 is of great significance for FAPbBr 3 SCs performance improvement.In this work, the key factors on the crystallization of δ-FAPbBr 3 and the effect of δ-FAPbBr 3 on device performance were systematically studied for the first time. The hydrophobic poly[bis(4phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) underlayer induces random growth of δ-FAPbBr 3 and its aggregation at the bottom of the perovskite films, which bring more defects and hinder carrier transport. Contrarily, δ-FAPbBr 3 has more regular crystallization and uniform distribution on the hydrophilic (2-(9H-carbazol-9-yl) ethyl) phosphonic acid (2PACz) underlayer, which has less defect states and better carrier transport. By virtue of the management of δ-FAPbBr 3 and the passivation of the upper interface with a phosphonate/phosphine oxide dyad molecule (PE-TPPO), a PCE of 9.12% was obtained, which is the highest efficiency among the inverted FAPbBr 3 SCs. A ST-SC reached a LUE of 3.15% with a PCE of 7.44% and an AVT of 42.31%.

Effective Energy Transfer Boosts Emission of Rare-Earth Double Perovskites: The Bridge Role of Sb(III) Doping

“…Lead-based halide perovskites, represented by APbX 3 (A = MA + /FA + /Cs + , X = Cl – /Br – /I – ), have garnered significant attention due to their exceptional photoelectric properties, including high light absorption coefficients, low defect densities, and large electronic dimensions . These Pb-based perovskites have been found to have wide-ranging applications in various fields, such as solar cells, − light-emitting diodes, − and X-ray detectors. − However, the inherent drawback of lead-based perovskites lies in their poor structural stability and propensity to release lead into the environment . The toxicity associated with lead is a severe concern, as it can have detrimental effects on children’s intelligence quotient and normal development .…”

“…These free excitons are then captured by the lattice distortion potential energy through dynamic Jahn− Teller distortion, resulting in the formation of STEs. Additionally, a portion of the excited electrons undergo intersystem crossing to the rare-earth energy level 5 D 4 and eventually return to the ground state through the rare-earth intrinsic luminescence ( 5 D 4 → 7 F J=6, 5,4,3 ). This overall photophysical process involving Sb 3+ ion doping enhances the luminescence efficiency of Cs 2 NaTbCl 6 by breaking the intrinsic forbidden transition, introducing new electron transition channels, and generating STEs.…”

Flexible, Transparent, and Bifacial Perovskite Solar Cells and Modules Using the Wide-Band Gap FAPbBr3 Perovskite Absorber

“…Among the strategies to increase the AVT are thickness tuning, patterning, and band gap tuning. ,, The optimal band gap range to achieve AVT values of 50–80% with the band gap tuning strategy is 2.18 and 2.32 eV . Formamidinium lead bromide (FAPbBr 3 ) perovskite, which has a band gap of around 2.3 eV, falls well within the optimal band gap range for achieving high AVT and has already demonstrated AVT values exceeding 50%. , The PCE of opaque FAPbBr 3 solar cells typically reaches around 10%. − However, when using semitransparent back-contact, PCE decreased to approximately 8%. ,, This reduction in efficiency is primarily attributed to the lack of back-reflection of the metallic back-contact, which results in a reduced collection of backscattered light for harvesting. Furthermore, semitransparent solar cells often employ a thinner absorber layer to enhance the AVT of the cell.…”

Multi‐Functional Spirobifluorene Phosphonate Based Exciplex Interface Enables Voc Reaching 95% of Theoretical Limit for Perovskite Solar Cells

“…Metal halide perovskites have attracted great attention in the photovoltaic field due to their outstanding optical and electrical properties. [1][2][3][4][5][6][7][8][9] The highly efficient perovskite solar cells (PSCs) DOI: 10.1002/adma.202313099 currently have achieved power conversion efficiency (PCE) over 26%. [10] However, the open-circuit voltage (V OC ) of devices still lags far behind the theoretical limit defined by the Shockley-Queisser theory; [11,12] especially for the PSCs based on the perovskites with bandgap wider than 1.6 eV, the V OC can only reach 80-90% of the theoretical limit, [13][14][15][16][17][18] which is mainly caused by the severe interface voltage loss originating from defects, energy level mismatch, and non-intimate contact between perovskites and charge transport layers.…”