Bifunctional Hole-Transport Materials with Modification and Passivation Effect for High-Performance Inverted Perovskite Solar Cells

Abstract

Hole-transport materials (HTMs) play an important role in perovskite solar cells (PSCs) to enhance the power conversion efficiency (PCE). The innovation of HTMs can increase the hole extraction ability and reduce interfacial recombination. Three organic small molecule HTMs with 4H-cyclopenta[2,1-b:3,4-b′]dithiophene (CPDT) as the central unit was designed and synthesized, namely, CPDTE-MTP (with the 2-ethylhexyl substituent and diphenylamine derivative end-group), CPDT-MTP (with the hexyl substituent and diphenylamine derivative end-group), and CPDT-PMTP (with the hexyl substituent and triphenylamine derivative end-group), which can form bifunctional and robust hole transport layer (HTL) on ITO and is tolerable to subsequent solvent and thermal processing. The X-ray photoelectron spectroscopy (XPS) results proved that CPDT-based HTMs can both interact with ITO through the nitrogen element in them and the tin element in ITO and passivate the upper perovskite layer. It is worth noting that the champion efficiency of MAPbI3 PSCs based on CPDT-PMTP achieved 20.77%, with an open circuit voltage (V OC) of 1.10 V, a short-circuit current (J SC) of 23.39 mA cm–2, and a fill factor (FF) of 80.83%, as three new materials were introduced into p–i–n PSCs as dopant-free HTMs.

Enhancing the Performance of Perovskite Solar Cells by Introducing 4-(Trifluoromethyl)-1H-imidazole Passivation Agents

“…After doping 0.16 wt% THI, both the two peaks shifted downward, from 143.5 eV and 138.6 eV of the pristine film to 143.3 eV and 138.4 eV, respectively. The lower binding energy suggested the interaction between the imidazole group in THI and the uncoordinated Pb 2+ in MAPbI 3 [ 33 ]. In addition, the XPS spectra of I 3d of the pristine and 0.16 THI MAPbI 3 films were also collected, as shown in Figure S1 .…”

Structural divergence of molecular hole selective materials for viable p-i-n perovskite photovoltaics: a comprehensive review

“…For instance, TPASF-based devices exhibited a better J sc /FF of 23.09 mA cm −2 /82.35% that led to a maximum PCE of 21% and retained 80% of their initial PCE for about 632 h under continuous maximum power point tracking (MPPT, 1000 h, 35 °C) under 1 sun illumination and ambient conditions which was better than the TPAOF (PCE: 19.99%) devices that exhibited a T80 lifetime of 430 h. Yuan et al incorporated 4Hcyclopenta[2,1- b :3,4- b ′]dithiophene (CPDT) as the central core unit with various terminal units such as a 2-ethylhexyl or hexyl substituent, and the diphenylamine donor unit was introduced to form CPDTE-MTP ( D31 ) or CPDT-MTP ( D32 ), respectively, while introducing a hexyl substituent and triphenylamine donor unit resulted in the formation of CPDT-PMTP ( D33 ). 163 All these materials exhibited a hydrophobic nature in which the water contact angles lie in the range of 71.2 to 81.9°. In comparison, they also exhibited good wettability with the DMF precursor solvent system (DMF contact angle: 8.54 to 11.42°) that resulted in the enlarged average size of the perovskite grains to 900 nm with CPDT-PMTP compared with 400 nm on a bare ITO substrate.…”

A Fluorination Strategy and Low‐Acidity Anchoring Group in Self‐Assembled Molecules for Efficient and Stable Inverted Perovskite Solar Cells

“…The short average decay lifetime of the MPA-2FBT-BA/perovskite film proved the effective charge extraction and transport by the use of MPA-2FBT-BA. [58][59] It is understood that the light intensity (I) dependence of the device is crucial for the studying the charge recombination during solar cell operation. Therefore, we examined the light intensity (I) dependence of V OC and J SC to elucidate the charge recombination process in solar cells, as depicted in Figure S12.…”