Chen Weijie

A green additive engineering method using fumaric acid (FMAC) is used to optimize the three‐cation perovskites. FMAC not only endows the perovskite films with a large grain size, but also stabilizes the perovskite crystal lattices and passivates the defects. Consequently, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) incorporating FMAC is increased to 20.48% from 19.18%.

Perovskite solar cells (PSCs) have debuted as the photovoltaic devices with the most potential and progress is being made at an unprecedented pace. Meanwhile, additive engineering is continuously pushing the power conversion efficiency (PCE) and device stability to higher levels by passivating defects and regulating crystallization behaviors. Considering the scalable fabrication of PSCs in the following stage, seeking green additives for optimizing perovskites is extremely valuable and paramount. Herein, we pioneer a green additive engineering method using fumaric acid (FMAC) to optimize the three‐cation perovskites to obtain highly efficient PSCs. FMAC not only optimizes crystallization behaviors to endow the perovskite films with a large grain size and few grain boundaries, but also forms a strong interaction with Pb²⁺/I⁻ of the perovskites, thereby stabilizing the [PbI₆]⁴⁻ octahedral framework of the perovskite crystal lattices and effectively passivating the surface defects. On this basis, FMAC improves the photoelectric properties of perovskites and in particular, suppresses the nonradiative recombination. Consequently, the PCE of PSCs incorporating FMAC rises to 20.48%, exceeding that (19.18%) of the pristine device. In addition, FMAC also enhances the stability of PSCs. Therefore, we provide a significant strategy using a green additive to enhance the photovoltaic performance of PSCs.

Perovskite solar cells (PSCs) have debuted as the photovoltaic devices with the most potential and progress is being made at an unprecedented pace. Meanwhile, additive engineering is continuously pushing the power conversion efficiency (PCE) and device stability to higher levels by passivating defects and regulating crystallization behaviors. Considering the scalable fabrication of PSCs in the following stage, seeking green additives for optimizing perovskites is extremely valuable and paramount. Herein, we pioneer a green additive engineering method using fumaric acid (FMAC) to optimize the three‐cation perovskites in order to obtain highly efficient PSCs. FMAC not only optimizes crystallization behaviors to endow the perovskite films with large grain size and few grain boundaries, but also forms a strong interaction with Pb²⁺/I⁻ of the perovskites, thereby stabilizing the [PbI₆]⁴⁻ octahedral framework of the perovskite crystal lattices and effectively passivating the surface defects. On this basis, FMAC improves the photoelectric properties of perovskites and in particular, suppresses the non‐radiative recombination. Consequently, the PCE of PSCs incorporating FMAC rises to 20.48%, exceeding that (19.18%) of the pristine device. In addition, FMAC also enhances the stability of PSCs. Therefore, we provide a significant strategy using a green additive to enhance the photovoltaic performance of PSCs.

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Strain widely exists in metal–halide perovskites (MHPs), and the presence of the residual strain greatly influences the optoelectronic properties of MHP film. Recently, many studies have reported the key role of strain engineering in improving the photovoltaic performance of perovskite solar cells (PSCs). Herein, current understanding and advanced strategies of strain engineering in PSCs are systematically summarized.

Due to the impressive optoelectronic properties, metal–halide perovskites (MHPs) have drawn much attention in the field of next‐generation photovoltaics, and perovskite solar cells (PSCs) based on MHPs as light absorbers have reached a certified power conversion efficiency (PCE) of 25.5% in 2020. Despite the great progress, it is still challenging to fabricate high‐quality MHP films. Due to the “soft” ionic nature of MHPs, their polycrystalline films suffer from inevitable residual strain, which is found to not only be fatal to photovoltaic performance of PSCs, but also seriously accelerate the degradation of MHP film. As a result, understanding of strain in MHPs and the key role of strain engineering in improving the photovoltaic performance of PSCs have recently been extensively investigated. Herein, the recent progress of strain engineering in MHPs and their PSCs is systematically summarized. First, the origin of strain in MHPs and the impact of strain on the optoelectronic characteristics of MHPs are carefully discussed. Thereafter, the up‐to‐date studies focusing on strain engineering in PSCs are comprehensively reviewed. At last, the current challenges and future prospects in this field are highlighted.

Dual‐isomer alkylammonium cation based 2D surface layer outperforms its single‐cation 2D counterparts in surface passivation quality, resulting in high‐performing (champion efficiency: 23.27%) PSCs, with an impressive open‐circuit voltage of 1.21 V for a perovskite composition with an optical bandgap of ≈1.6 eV.

Abstract

Dimensional engineering of perovskite solar cells has attracted significant research attention recently because of the potential to improve both device performance and stability. Here, a novel 2D passivation scheme for 3D perovskite solar cells is demonstrated using a mixed cation composition of 2D perovskite based on two different isomers of butylammonium iodide. The dual‐cation 2D perovskite outperforms its single cation 2D counterparts in surface passivation quality, resulting in devices with an impressive open‐circuit voltage of 1.21 V for a perovskite composition with an optical bandgap of ≈1.6 eV, and a champion efficiency of 23.27%. Using a combination of surface elemental analysis and valence electron spectra decomposition, it is shown that an in situ interaction between the 2D perovskite precursor and the 3D active layer results in surface intermixing of 3D and 2D perovskite phases, providing an effective combination of defect passivation and enhanced charge transfer, despite the semi‐insulating nature of the 2D perovskite phase. The demonstration of the synergistic interaction of multiple organic spacer cations in a 2D passivation layer offers new opportunities for further enhancement of device performance with mixed dimensional perovskite solar cells.

Three benzo[1,2‐b:4,5‐b']dithiophene‐thienothiophene π‐bridged N‐octylthieno[3,4‐c]pyrrole‐4,6‐dione‐based polymer donors named as PBDT‐X (X=H, F, Cl) are developed. While a planar accepting unit helps improve the crystallinity, all three photovoltaic parameters are simultaneously increased with the introduction of halogen atoms. PBDT‐Cl:Y6‐based devices yield an efficiency of 15.63%, attributed to the enhanced crystallinity, hole mobility, and domain purity.

Abstract

In this work, a new series of polymer donors consisting of thienothiophene π‐bridged N‐octylthieno[3,4‐c]pyrrole‐4,6‐dione (8ttTPD) and benzo[1,2‐b:4,5‐b']dithiophene (BDT) units for producing highly efficient organic solar cells (OSCs) paired with a Y6 acceptor is developed. The incorporation of the highly planar 8ttTPD unit enhances crystalline properties as well as hole mobilities of the BDT‐based polymers that typically have amorphous features. Further, the 2D side chains with halogen atoms (fluorine and chlorine) are designed as another handle to control the crystallinity and energy levels of the BDT‐based polymer donors: PBDT‐X (X = H, F, or Cl). Synergistic effects of incorporated 8ttTPD unit and the halogenated 2D side chain generate significantly enhanced charge transport and recombination properties of the OSCs, which is mainly attributed to optimized crystallinity and hole mobility of the polymer donors. Therefore, the PBDT‐Cl:Y6‐based OSCs exhibit the highest power conversion efficiency (PCE) of 15.63% with simultaneous improvements of open‐circuit voltage, short‐circuit current density, and fill factor, which outperforms the PCEs of PBDT‐H:Y6 (11.84%) and PBDT‐F:Y6 (14.86%).

Herein, novel Ruddlesden–Popper Cs₂PbI₂Cl₂ nanosheets are synthesized and creatively employed as a multifunctional interface optimization material to improve the performance of CsPbI₂Br solar cells. Based on the heterostructured NSs/CsPbI₂Br/NSs inorganic film, an efficiency of 16.65% is obtained, which is one of the best reported for CsPbI₂Br solar cells, along with much‐enhanced UV, air, and thermal stabilities.

Abstract

Inorganic CsPbI₂Br perovskite solar cells (PSCs) have gained enormous research interest due to their excellent thermal and light stabilities. However, their unsatisfactory power‐conversion efficiency and poor intrinsic phase stability remain roadblocks to their further development. Herein, Cs₂PbI₂Cl₂ nanosheets (NSs) with the Ruddlesden–Popper (RP) structure are synthesized, and an NSs/CsPbI₂Br/NSs heterostructure is employed to enhance both the stability and efficiency of CsPbI₂Br solar cells. The novel Cs₂PbI₂Cl₂ NSs can not only passivate the top and bottom surfaces of the perovskite film and top surface of the TiO₂ film but also enhance the stability of the perovskite film. Based on the heterostructured NSs/CsPbI₂Br/NSs inorganic perovskite film, the efficiency of the CsPbI₂Br PSCs is improved from 15.02% to 16.65%. Moreover, the unencapsulated CsPbI₂Br devices with the NSs/CsPbI₂Br/NSs heterostructure sustain over 90% of their original efficiencies after being exposed to ambient conditions (≈25 °C and ≈35% RH) for 648 h. Both the UV‐light‐soaking stability (100 mW cm⁻¹ 365 nm UV light) and thermal stability (T = 85 °C) of the optimized devices are dramatically improved in comparison with their counterparts with only a 3D active layer. Therefore, this work promotes the application of RP inorganic perovskite nanocrystals in a range of perovskite optoelectronic devices.

A newly conceived n‐type small molecule (Y‐Th2) is incorporated as an efficient additive in perovskite solar cells, achieving simultaneous improvements in device performance and stability. Y‐Th2 effectively passivates defects in perovskite crystals by Lewis acid–base interactions and intermolecular hydrogen bonds, obtaining high‐quality perovskite film. The inverted structure device exhibits a power conversion efficiency of 21.5% with notably enhanced operational stability.

Abstract

Significant efforts have been devoted to modulating the grain size and improving the film quality of perovskite in perovskite solar cells (PSCs). Adding materials to the perovskite is especially promising for high‐performance PSCs, because the additives effectively control the crystal structure. Although the additive engineering approach has substantially boosted the efficiency of PSCs, instability of the perovskite film has remained a primary bottleneck for the commercialization of PSCs. Herein, a newly conceived bithiophene‐based n‐type conjugated small molecule (Y‐Th2) is introduced to PSCs, which simultaneously enhances the performance and stability of the cell. The Y‐Th2 effectively passivates the defect states in perovskite through Lewis acid–base interactions, increasing the grain size and quality of the perovskite absorber. An inverted PSC containing the Y‐Th2 additive achieves a power conversion efficiency of 21.5%, versus 18.3% in the reference device. The operational stability is also considerably enhanced by the improved hydrophobicity and intermolecular hydrogen bonds in the perovskite.

This work is the first to integrate the multimechanism recombination parameters with the density of states (DOS) distribution and effective bandgap in the framework of a semiempirical analytical model of temperature and light intensity dependent V _oc. The proposed approach is expected to be a useful tool for quantifying the full spectrum of recombination‐ and DOS‐related parameters of nonfullerene organic solar cells.

Abstract

The relationship of the temperature–light intensity dependence of open‐circuit voltage V _oc in nonfullerene‐based organic solar cells with their material characteristics and multimechanism recombination parameters is described. The systematic variation of the effective bandgap E _g,eff and the electrode layers allows the observation of different relative contributions of bimolecular, bulk, and surface trap‐assisted recombination mechanisms. The complementary advantages of the analytical model and the established voltage‐impedance spectroscopy technique provide a useful tool to quantify multimechanism recombination parameters, effective density of states N _c, and energetic disorder σ in organic solar cells under operating conditions. The validity of the proposed model to understand the temperature and light intensity dependent of V _oc is shown by applying it to four different donor:nonfullerene acceptor blend systems with conventional or inverted device architectures.

Molecular packing and thermodynamic properties of D18‐based fullerene‐free organic solar cells are studied. The D18 polymer exhibits strong chain extension in films, which is beneficial to charge transport. Miscibility and other characterizations explain the disparate performance of three systems and the processing procedures.

Abstract

Organic solar cells (OSCs) based on D18:Y6 have recently exhibited a record power conversion efficiency of over 18%. The initial work is extended and the device performance of D18‐based OSCs is compared with three non‐fullerene acceptors, Y6, IT‐4F, and IEICO‐4Cl, and their molecular packing characteristics and miscibility are studied. The D18 polymer shows unusually strong chain extension and excellent backbone ordering in all films, which likely contributes to the excellent hole‐transporting properties. Thermodynamic characterization indicates a room‐temperature miscibility for D18:Y6 and D18:IT‐4F near the percolation threshold. This corresponds to an ideal quench depth and explains the use of solvent vapor annealing rather than thermal annealing. In contrast, D18:IEICO‐4Cl is a low‐miscibility system with a deep quench depth during casting and poor morphology control and low performance. A failure of ternary blends with PC₇₁BM is likely due to the near‐ideal miscibility of Y6 to begin with and indicates that strategies for developing successful ternary or quaternary solar cells are likely very different for D18 than for other high‐performing donors. This work reveals several unique property–performance relations of D18‐based photovoltaic devices and helps guide design or fabrication of yet higher efficiency OSCs.

The fabrication challenges of monolithic all‐perovskite tandem photovoltaics are detailed in a step‐by‐step, choose‐your‐own‐adventure fashion. The trade‐offs between sub‐cell efficiency and processing stability are highlighted and pros and cons are weighed. Through this detailed analysis, a few routes to reach >30% power conversion efficiency and the necessary work are identified.

Abstract

Metal halide perovskites (MHPs) have transfixed the photovoltaic (PV) community due to their outstanding and tunable optoelectronic properties coupled to demonstrations of high‐power conversion efficiencies (PCE) at a range of bandgaps. This has motivated the field to push perovskites to reach the highest possible performance. One way to increase the efficiency is by fabricating multijunction solar cells, which can split the solar spectrum, reducing thermalization loss. Low‐cost all‐perovskite tandems have a real chance to soon exceed 30% PCE, which could transform the PV industry. Achieving this goal requires the identification of perovskite sub‐cells that are both highly efficient and can be effectively integrated. Herein, it is discussed how to navigate the multiple‐choice adventure in choosing between the myriad of options and considerations present when deciding what perovskite materials, contact layers, and processing tools to use. Some of the potential fabrication pitfalls often encountered in MHP based tandem PVs are highlighted, so that they can hopefully be avoided in the future.

One big challenge for long-lived inverted perovskite solar cells (PSCs) is that commonly used metal electrodes react with perovskite layer, inducing electrode corrosion and device degradation. Motivated by the idea of metal anticorrosion, here, we propose a chemical anticorrosion strategy to fabricate stable inverted PSCs through introducing a typical organic corrosion inhibitor of benzotriazole (BTA) before Cu electrode deposition. BTA molecules chemically coordinate to the Cu electrode and form an insoluble and polymeric film of [BTA-Cu], suppressing the electrochemical corrosion and reaction between perovskite and the Cu electrode. PSCs with BTA/Cu show excellent air stability, retaining 92.8 ± 1.9% of initial efficiency after aging for 2500 hours. In addition, >90% of initial efficiency is retained after 85°C aging for over 1000 hours. PSCs with BTA/Cu also exhibit good operational stability, and 88.6 ± 2.6% of initial efficiency is retained after continuous maximum power point tracking for 1000 hours.

We disclosed a key finding to modulate the crystallization kinetics of FASnI₃ through a non‐classical nucleation mechanism based on pre‐nucleation clusters. A direct link between the colloids in the perovskite precursor solution and final optoelectronic quality of the perovskite films was established. Finally, power conversion efficiency of 11.39 % was obtained for FASnI₃‐based perovskite solar cells.

Abstract

Tin halide perovskites are rising as promising materials for lead‐free perovskite solar cells (PSCs). However, the crystallization rate of tin halide perovskites is much faster than the lead‐based analogs, leading to more rampant trap states and lower efficiency. Here, we disclose a key finding to modulate the crystallization kinetics of FASnI₃ through a non‐classical nucleation mechanism based on pre‐nucleation clusters (PNCs). By introducing piperazine dihydriodide to tune the colloidal chemistry of the FASnI₃ perovskite precursor solution, stable clusters could be readily formed in the solution before nucleation. These pre‐nucleation clusters act as intermediate phase and thus can reduce the energy barrier for the perovskite nucleation, resulting in a high‐quality perovskite film with lower defect density. This PNCs‐based method has led to a conspicuous photovoltaic performance improvement for FASnI₃‐based PSCs, delivering an impressive efficiency of 11.39 % plus improved stability.

Annual energy yield of perovskite/silicon tandem solar cells under monofacial and bifacial illumination as a function of the perovskite bandgap. The effect of luminescent coupling (LC)–light emitted by the perovskite cell and re‐utilized by the silicon cell–is investigated. LC relaxes the constraints on the top‐cell bandgap, which is important for developing optimal perovskite materials for tandem photovoltaics.

The power conversion efficiency of the market‐dominating silicon photovoltaics approaches its theoretical limit. Bifacial solar operation with harvesting additional light impinging on the module back and the perovskite/silicon tandem device architecture are among the most promising approaches for further increasing the energy yield from a limited area. Herein, the energy output of perovskite/silicon tandem solar cells in monofacial and bifacial operation is calculated, for the first time considering luminescent coupling (LC) between two sub‐cells. For energy yield calculations, idealized solar cells are studied at both standard testing as well as realistic weather conditions in combination with a detailed illumination model for periodic solar panel arrays. Typical experimental photoluminescent quantum yield values reveal that more than 50% of excess electron–hole pairs in the perovskite top cell can be utilized by the silicon bottom cell by means of LC. As a result, LC strongly relaxes the constraints on the top‐cell bandgap in monolithic tandem devices. In combination with bifacial operation, the optimum perovskite bandgap shifts from 1.71 eV to the range 1.60–1.65 eV, where already high‐quality perovskite materials exist. The results are very important for developing optimal perovskite materials for tandem solar cells.

Ligand exchange is performed on PbS colloidal quantum dots using conventional PbX₂ ligands and KI₃ additives via a facile one‐step process, which simultaneously eliminate the undesirable sites and efficiently passivate the surface. The resulting solar cells achieve a power conversion efficiency of 12.1%.

Abstract

The surface chemistry of colloidal quantum dots (CQD) play a crucial role in fabricating highly efficient and stable solar cells. However, as‐synthesized PbS CQDs are significantly off‐stoichiometric and contain inhomogeneously distributed S and Pb atoms at the surface, which results in undercharged Pb atoms, dangling bonds of S atoms and uncapped sites, thus causing surface trap states. Moreover, conventional ligand exchange processes cannot efficiently eliminate these undesired atom configurations and defect sites. Here, potassium triiodide (KI₃) additives are combined with conventional PbX₂ matrix ligands to simultaneously eliminate the undercharged Pb species and dangling S sites via reacting with molecular I₂ generated from the reversible reaction KI₃ ⇌ I₂ + KI. Meanwhile, high surface coverage shells on PbS CQDs are built via PbX₂ and KI ligands. The implementation of KI₃ additives remarkably suppresses the surface trap states and enhances the device stability due to the surface chemistry optimization. The resultant solar cells achieve the best power convention efficiency of 12.1% and retain 94% of its initial efficiency under 20 h continuous operation in air, while the control devices with KI additive deliver an efficiency of 11.0% and retains 87% of their initial efficiency under the same conditions.

An additive‐involved leaching method is proposed to reduce the preparation temperature of CsPbI₃ to 100 °C. The CsPbI₃ perovskite film with high crystallinity is formed by an ion exchange reaction between DMAPbI₃ and Cs₄PbI₆. More than 16% photoelectric conversion efficiency can be achieved and the inencapsulation device exhibits remaekable stability.

Abstract

Inorganic CsPbI₃ perovskite with an optical bandgap ranging from 1.67 to 1.75 eV is a promising light‐harvesting material as a top cell in tandem solar cells, but its high fabrication temperature can damage the middle layers or the bottom subcells. Here, an additive‐involved leaching method to fabricate CsPbI₃ perovskite films is demonstrated, which can decrease the preparation temperature to 100 °C. The CsPbI₃ perovskite films with high crystallinity are achieved by a solution assisted reaction between DMAPbI₃ and Cs₄PbI₆ with the leaching of DMA⁺, Cs⁺, and I⁻. The as‐prepared CsPbI₃ perovskite films exhibit much superior stability compared to their high‐temperature counterparts. As a result, a power conversion efficiency of over 16% is obtained, and the unencapsulated device maintains over 93% of the initial efficiency after aging for 30 days in air with a relative humidity of 10%.

Publication date: March 2021

Source: Nano Energy, Volume 81

Author(s): Yutong Ren, Ming Ren, Xinrui Xie, Jianan Wang, Yaohang Cai, Yi Yuan, Jing Zhang, Peng Wang

A low‐temperature solution‐processed, annealing‐free, amorphous metal oxyhydroxide cathode interlayer is used to facilitate charge extraction and suppress interfacial charge recombination in inverted perovskite photovoltaics, delivering a power conversion efficiency of 21.3%.

The state‐of‐the‐art high‐performance perovskite solar cells (PSCs) with inverted p‐i‐n device structure normally use crystalline metal oxide materials or organic small molecules as the cathode interlayer between the fullerene layer and metal electrode. However, these interlayers are made by either high‐temperature or complicated vacuum‐assisted fabrication process, and in many cases, they are not efficient and effective enough to simultaneously extract the electrons and suppress the interfacial charge recombination. Herein, for the first time, a facile low‐temperature solution‐processed strategy is demonstrated to fabricate an amorphous metal oxyhydroxide (a‐MOH) thin film, which is used as a robust cathode interlayer in inverted PSCs. The a‐MOH interlayer not only facilitates electron extraction and collection via “energy‐favorable” electron tunneling, but also suppresses the interfacial charge recombination via effective hole blocking and electron backflow inhibition. As a result, the PSCs based on a‐MOH interlayer achieve a stabilized power conversion efficiency (PCE) of 21.1% and retain 93% of initial PCE after continuous one‐sun illumination for 500 hours.

A C₃N₄ layer functionalized with thiazole is introduced to the electron transfer layer/perovskite interface, which serves as an intermediate energy level to constitute a stepwise energy band alignment and donates the lone pair electrons to undercoordinated Pb²⁺. Resultantly, it effectively passivates the interfacial defects and promotes carrier transport, thereby further boosting the efficiency of the device.

Despite the conspicuous achievements in perovskite solar cells (PSCs), further improvement of the power conversion efficiency (PCE) is hindered by substantially detrimental carrier recombination resulting from the high interfacial charge defect density and inferior charge transport kinetics. Herein, an interface engineering strategy is developed to introduce a Lewis base thiophene or thiazole–modified C₃N₄ layer at the electron transfer layer (ETL)/perovskite interface to constitute a stepwise energy band alignment and passivate defects at interfaces of the perovskite film. Attributed to its well‐matched energy level with TiO₂ and perovskite, the charge extraction efficiency and charge transfer dynamics can be promoted remarkably, greatly inhibiting charge recombination at the interface. Furthermore, thiophene and thiazole can donate the lone pair electrons in S or N atoms to undercoordinated Pb²⁺, which effectively passivates the electronic trap states caused by halogen vacancies, thereby greatly minimizing trap‐assisted nonradiative recombination in the PSCs. Eventually, the thiazole–C₃N₄/perovskite‐based devices acquire an outstanding efficiency of 19.23%, supported by an enhanced open‐circuit voltage (V _OC) of 1.11 V with improved moisture stability. This work provides an avenue for interfacial energy level modulation and defect passivation strategies for a rational interface microstructure design for meliorating the performance of PSCs.

A straightforward polyTPD passivation is introduced to reduce the defect‐mediated recombination by elucidating the imperfections on the surface and grain boundaries of perovskite materials. Suppressed non‐radiative recombination and improved interfacial hole extraction result in perovskite solar cells with stabilized efficiency exceeding 21%. Moreover, ultra‐hydrophobic and thermally robust polyTPD passivated devices retain 94% of the initial efficiency after 800 h under operational conditions.

Abstract

The failure of perovskite solar cells (PSCs) to maintain their maximum efficiency over a prolonged time is due to the deterioration of the light harvesting material under environmental factors such as humidity, heat, and light. Systematically elucidating and eliminating such degradation pathways are critical to imminent commercial use of this technology. Here, a straightforward approach is introduced to reduce the level of defect‐states present at the perovskite and hole transporting layer interface by treating the various perovskite surfaces with poly(N,N′‐bis‐4‐butylphenyl‐N,N′‐bisphenyl)benzidine (polyTPD) molecules. This strategy significantly suppresses the defect‐mediated non‐radiative recombination in the ensuing devices and prevents the penetration of degrading agents into the inner layers by passivating the perovskite surface and grain boundaries. Suppressed non‐radiative recombination and improved interfacial hole extraction result in PSCs with stabilized efficiency exceeding 21% with negligible hysteresis (≈19.1% for control device). Moreover, ultra‐hydrophobic polyTPD passivant considerably alleviates moisture penetration, showing ≈91% retention of initial efficiencies after 300 h storage at high relative humidity of 80%. Similarly, passivated device retains 94% of its initial efficiency after 800 h under operational conditions (maximum power point tracking under continuous illumination at 60 °C). In addition to interfacial passivation function, hole‐selective role of dopant‐free polyTPD is also evaluated and discussed in this study.