Material and Interface Engineering for High‐Performance Perovskite Solar Cells: A Personal Journey and Perspective

Abstract

Hybrid organic‐inorganic perovskite solar cells (PSCs) have become a shining star in the photovoltaic field due to their spectacular increase in power conversion efficiency (PCE) from 3.8 % to over 23 % in just few years, opening up the potential in addressing the important future energy and environment issues. The excellent photovoltaic performance can be attributed to the unique properties of the organometal halide perovskite materials, including high absorption coefficient, tunable bandgap, high defect tolerance, and excellent charge transport characteristics. The authors entered this field when pursuing research on dye‐sensitized solar cells (DSCs) by leveraging nanorods arrays for vectorial transport of the extracted electrons. Soon after, we and others realized that while the organometal halide perovskite materials have excellent intrinsic properties for solar cells, interface engineering is at least equally important in the development of high‐performance PSCs, which includes surface defect passivation, band alignment, and heterojunction formation. Herein, we will address this topic by presenting the historical development and recent progress on the interface engineering of PSCs primarily of our own group. This review is mainly focused on the material and interface design of the conventional n‐i‐p, inverted p‐i‐n and carbon electrode‐based structure devices from our own experience and perspective. Finally, the challenges and prospects of this area for future development will also be discussed.

Photonic Structuration of Hybrid Inverse-Opal TiO2—Perovskite Layers for Enhanced Light Absorption in Solar Cells

“…In n-i-p configurations of PSCs, , TiO 2 photoanodes in their whole are commonly composed of two components: a thin (∼50 nm) compact TiO 2 sublayer, guaranteeing the coverage of the carrier collector electrode (such as a fluorine-doped tin oxideFTOtransparent conducting layer covering the glass substrate), and a thicker mesoporous TiO 2 “top layer”, allowing for the collection of most of the electrons generated in the perovskite photoabsorber as well as their transport through the TiO 2 porous network to the compact TiO 2 layer and then to the FTO electrode. The tuning of the morphology of this porous TiO 2 top layer, directly in contact with the perovskite photoabsorbing material, is thus crucial, not only for managing the photoelectrons transfers but also for specifically improving the light absorption efficiency through rational photonic structuration of the TiO 2 –perovskite interface. , Crucially, to specifically consider the photonic enhancement aspects, this study focuses on pore radius R values localized around 200 nm, concretely in the 100–300 nm range (or diameter d ∼ 200–600 nm).…”

“…Specifically, photonic structuration as a strategic approach for designing novel efficient photovoltaic (PV) materials and devices has shown its suitability in improving the global energy conversion by directly enhancing light absorption without increasing the quantity of photoactive component(s). , This observation has been particularly verified in the emerging generation of hybrid organic–inorganic solar cells made of lead halide perovskites: their structural, optical, and electronic benefits have indeed been increasingly acknowledged in the past ten years in terms of improved light absorption, carrier mobility, and diffusion length as well as low fabrication costs. − Perovskite solar cells (PSCs) currently reach power conversion efficiency (PCE) values as high as 25.5%, making them much competitive with crystalline Si solar cells and other thin film-based PV technologies . The implementation of PCs into PSCs, despite being quite challenging in terms of conceptual design and experimental processability, is particularly promising: in addition to showing enhanced light management and PCE capacities, PSCs displaying photonic nanostructures can further testify for color tunability and aesthetical adaptability, which are of noticeable interest for incorporation into wearable or building-integrated PV appliances. − …”

Enhanced Device Performance of Perovskite Photovoltaics by Magnetic Field‐Aligned Perovskites‐Magnetic Nanoparticles Composite Thin Film

“…The R S consists of the sheet resistance (R Sheet ) of the electrodes, and the charge-transfer resistance (R CT ) at the interfaces between the electrode and the charge carrier extraction layers, as well as the interface between the charge carrier extraction layer and perovskite layer. [61][62][63][64] In this study, all PSCs have the same device structure; the only difference is in perovskite layer. Thus, the equivalent electric circuit (also called RC circuit model) shown in the inset of Figure 3b can be used to describe PSCs.…”

Photo-stable perovskite solar cells with reduced interfacial recombination losses using a CeOx interlayer

“…The addition of interlayers between the CTLs and perovskite absorber has proven to be an efficient method to mitigate interfacial recombination losses [10][11][12]. For the interface between the electron transport layer (ETL) and perovskite, a broad range of interlayer materials, including metal oxides, conjugated polymers, small molecules, and fullerenes, has been reported [13][14][15]. Among these, metal-oxide interlayers are frequently used in PSCs owing to their good chemical stability, which endows the interlayers with robust (solvent-resistant) properties [16][17][18][19][20].…”