High‐efficiency and low‐cost perovskite solar cells (PVKSCs) are an ideal candidate for addressing the scalability challenge of solar‐based renewable energy. The dynamically evolving research field ...of PVKSCs has made immense progress in solving inherent challenges and capitalizing on their unique structure–property–processing–performance traits. This review offers a unique outlook on the paths toward commercialization of PVKSCs from the interfacial engineering perspective, relevant to both specialists and nonspecialists in the field through a brief introduction of the background of the field, current state‐of‐the‐art evolution, and future research prospects. The multifaceted role of interfaces in facilitating PVKSC development is explained. Beneficial impacts of diverse charge‐transporting materials and interfacial modifications are summarized. In addition, the role of interfaces in improving efficiency and stability for all emerging areas of PVKSC design are also evaluated. The authors' integral contributions in this area are highlighted on all fronts. Finally, future research opportunities for interfacial material development and applications along with scalability–durability–sustainability considerations pivotal for facilitating laboratory to industry translation are presented.
The multifaceted roles of interfacial engineering in the evolution of highly efficient and stable perovskite solar cells are explained. Unique structure–property–processing–performance traits are summarized. Functions of diverse charge transport materials and interfacial modifications are comprehensively discussed. Scalability–durability–sustainability considerations for commercialization are highlighted. Prospective research directions are presented for all developmental fronts.
Low‐temperature, solution‐processable Cu‐doped NiOX (Cu:NiOx), prepared via combustion chemistry, is demonstrated as an excellent hole‐transporting layer (HTL) for thin‐film perovskite solar cells ...(PVSCs). Its good crystallinity, conductivity, and hole‐extraction properties enable the derived PVSC to have a high power conversion efficiency (PCE) of 17.74%. Its general applicability for various elecrode materials is also revealed.
Highly crystalline SnO2 is demonstrated to serve as a stable and robust electron‐transporting layer for high‐performance perovskite solar cells. Benefiting from its high crystallinity, the relatively ...thick SnO2 electron‐transporting layer (≈120 nm) provides a respectable electron‐transporting property to yield a promising power conversion efficiency (PCE)(18.8%) Over 90% of the initial PCE can be retained after 30 d storage in ambient with ≈70% relative humidity.
Extremely high power conversion efficiencies (PCEs) of ≈20–22% are realized through intensive research and development of 1.5–1.6 eV bandgap perovskite absorbers. However, development of ideal ...bandgap (1.3–1.4 eV) absorbers is pivotal to further improve PCE of single junction perovskite solar cells (PVSCs) because of a better balance between absorption loss of sub‐bandgap photons and thermalization loss of above‐bandgap photons as demonstrated by the Shockley–Queisser detailed balanced calculation. Ideal bandgap PVSCs are currently hindered by the poor optoelectronic quality of perovskite absorbers and their PCEs have stagnated at <15%. In this work, through systematic photoluminescence and photovoltaic analysis, a new ideal bandgap (1.35 eV) absorber composition (MAPb0.5Sn0.5(I0.8Br0.2)3) is rationally designed and developed, which possesses lower nonradiative recombination states, band edge disorder, and Urbach energy coupled with a higher absorption coefficient, which yields a reduced Voc,loss (0.45 V) and improved PCE (as high as 17.63%) for the derived PVSCs. This work provides a promising platform for unleashing the complete potential of ideal bandgap PVSCs and prospects for further improvement.
An ideal‐bandgap (1.35 eV) perovskite (MAPb0.5Sn0.5(I0.8Br0.2)3) is developed with lower non‐radiative recombination states, band edge disorder, and Urbach energy coupled with a higher absorption coefficient, yielding a reduced open‐circuit voltage loss of 0.45 V and improved efficiency of 17.63%. This work provides a promising platform for unleashing the complete potential of ideal‐bandgap perovskite solar cells.
In this paper, an electron donor–acceptor (D-A) substituted dipolar chromophore (BTPA-TCNE) is developed to serve as an efficient dopant-free hole-transporting material (HTM) for perovskite solar ...cells (PVSCs). BTPA-TCNE is synthesized via a simple reaction between a triphenylamine-based Michler’s base and tetracyanoethylene. This chromophore possesses a zwitterionic resonance structure in the ground state, as evidenced by X-ray crystallography and transient absorption spectroscopies. Moreover, BTPA-TCNE shows an antiparallel molecular packing (i.e., centrosymmetric dimers) in its crystalline state, which cancels out its overall molecular dipole moment to facilitate charge transport. As a result, BTPA-TCNE can be employed as an effective dopant-free HTM to realize an efficient (PCE ≈ 17.0%) PVSC in the conventional n-i-p configuration, outperforming the control device with doped spiro-OMeTAD HTM.
A low‐bandgap (1.33 eV) Sn‐based MA0.5FA0.5Pb0.75Sn0.25I3 perovskite is developed via combined compositional, process, and interfacial engineering. It can deliver a high power conversion efficiency ...(PCE) of 14.19%. Finally, a four‐terminal all‐perovskite tandem solar cell is demonstrated by combining this low‐bandgap cell with a semitransparent MAPbI3 cell to achieve a high efficiency of 19.08%.
Fluorinated n‐type conjugated polymers are used as efficient electron acceptor to demonstrate high‐performance all‐polymer solar cells. The exciton generation, dissociation, and charge‐transporting ...properties of blend films are improved by using these fluorinated n‐type polymers to result in enhanced photocurrent and suppressed charge recombination.
Wide bandgap MAPb(I1–y Br y )3 perovskites show promising potential for application in tandem solar cells. However, unstable photovoltaic performance caused by phase segregation has been observed ...under illumination when y is above 0.2. Herein, we successfully demonstrate stabilization of the I/Br phase by partially replacing Pb2+ with Sn2+ and verify this stabilization with X-ray diffractometry and transient absorption spectroscopy. The resulting MAPb0.75Sn0.25(I1–y Br y )3 perovskite solar cells show stable photovoltaic performance under continuous illumination. Among these cells, the one based on MAPb0.75Sn0.25(I0.4Br0.6)3 perovskite shows the highest efficiency of 12.59% with a bandgap of 1.73 eV, which make it a promising wide bandgap candidate for application in tandem solar cells. The engineering of internal bonding environment by partial Sn substitution is believed to be the main reason for making MAPb0.75Sn0.25(I1–y Br y )3 perovskite less vulnerable to phase segregation during the photostriction under illumination. Therefore, this study establishes composition engineering of the metal site as a promising strategy to impart phase stability in hybrid perovskites under illumination.
Organic–inorganic hybrid perovskite multijunction solar cells have immense potential to realize power conversion efficiencies (PCEs) beyond the Shockley–Queisser limit of single‐junction solar cells; ...however, they are limited by large nonideal photovoltage loss (V
oc,loss) in small‐ and large‐bandgap subcells. Here, an integrated approach is utilized to improve the V
oc of subcells with optimized bandgaps and fabricate perovskite–perovskite tandem solar cells with small V
oc,loss. A fullerene variant, Indene‐C60 bis‐adduct, is used to achieve optimized interfacial contact in a small‐bandgap (≈1.2 eV) subcell, which facilitates higher quasi‐Fermi level splitting, reduces nonradiative recombination, alleviates hysteresis instabilities, and improves V
oc to 0.84 V. Compositional engineering of large‐bandgap (≈1.8 eV) perovskite is employed to realize a subcell with a transparent top electrode and photostabilized V
oc of 1.22 V. The resultant monolithic perovskite–perovskite tandem solar cell shows a high V
oc of 1.98 V (approaching 80% of the theoretical limit) and a stabilized PCE of 18.5%. The significantly minimized nonideal V
oc,loss is better than state‐of‐the‐art silicon–perovskite tandem solar cells, which highlights the prospects of using perovskite–perovskite tandems for solar‐energy generation. It also unlocks opportunities for solar water splitting using hybrid perovskites with solar‐to‐hydrogen efficiencies beyond 15%.
High open‐circuit voltage, V
oc (1.98 V) and power conversion efficiency, PCE (18.5%) is realized in an ideal bandgap‐matched two‐terminal perovskite–perovskite tandem solar cell via an integrated approach. A fullerene variant, Indene‐C60 bis‐adduct is used to achieve optimized interfacial contact and alleviate hysteresis instabilities in the small‐bandgap subcell. Compositional engineering is employed to realize more highly photostabilized V
oc in the large‐bandgap subcell.
In this review, we summarize the latest developments in solution-processed interfacial layers that have contributed to the significantly improved performance of polymer and perovskite solar cells ...(PSCs and PVSCs). The solution-processed interfacial materials, including organic electrolytes, organic-inorganic hybrids, graphene oxides (GOs), transition metal oxides (TMOs), and self-assembled functional materials, along with their integration into efficient PSCs, polymer tandem cells (PTCs), and the emerging perovskite solar cells (PVSCs) are discussed. Regarding the rapid progress of PSCs and PVSCs, strategies and perspectives of further improving solution-processed interfacial materials are also discussed to help readers understand the challenges and opportunities in transitioning from scientific curiosity into technology translation for realizing low-cost, printable, and high-efficiency flexible solar cells to address the scalability issues facing solar energy.
The latest developments in solution-processed interfacial layers for polymer and hybrid perovskite solar cells are comprehensively reviewed in this article.
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