Introduction of scalable deposition methods along with morphological control of the film will be provided in the review.

Shorter diffusion length of the electrons than that of the holes is one of the major limitations to boost efficiency of perovskite hybrid solar cells (pero-HSCs). To facilitate electron extraction efficiency in pero-HSCs and make it comparable to that of hole, we, for the first time, demonstrate bulk heterojuncion (BHJ) pero-HSCs fabricated by the mixture of perovskite materials with water/alcohol-soluble fullerene derivatives rather than pristine perovskite materials. Balanced charge carrier extraction efficiency and enlarged interfacial area between perovskite materials and fullerene derivatives are response for enhanced short circuit current densities (J SC ) and enlarged fill factors (FF), consequently, significantly improved power conversion efficiency (PCE) of BHJ pero-HSCs. As compared with planar heterojunction pero-HSCs, more than 22% enhancement in PCE is observed from BHJ pero-HSCs. Remarkable, 86.7% of FF, the highest value for pero-HSCs, is observed from BHJ pero-HSCs. Our strategy of using BHJ structure in pero-HSCs offers an efficient and simple way to further boost the device performance. thin films shown in Figure 9b are inhomogeneous.The inhomogeneous crystal domain observed from CH 3 NH 3 PbI 3 :A 10 C 60 BHJ composite thin films have two different sizes: the one with the domain sizes which are identical to those found in Figure 9a, is probably from CH 3 NH 3 PbI 3 polycrystals; while the other with different domain sizes is probably from A 10 C 60 crystals.The cross-sectional SEM images of ITOBM are displayed in Figures 9e & 9f, respectively. The thickness of each layer is consistent to that in the final devices. Figure 9e shows a PHJ structure of CH 3 NH 3 PbI 3 /PC 61 BM, where the pristine CH 3 NH 3 PbI 3 layer is sandwiched between PEDOT:PSS layer and PC 61 BM ETL. In contrast, in Figure 9f, the CH 3 NH 3 PbI 3 :A 10 C 60 composite layer is sandwiched between PEDOT:PSS layer and PC 61 BM ETL. Moreover, the A 10 C 60 domains can be clearly found in CH 3 NH 3 PbI 3 :A 10 C 60 composite layer. This observation evidently confirms that A 10 C 60 is mixed with CH 3 NH 3 PbI 3 to form CH 3 NH 3 PbI 3 :A 10 C 60 BHJ composite layer.In order to further understand underlying device performance of both PHJ and BHJ pero-HSCs, the investigation of photoluminescence (PL) of BM thin films are conducted. Figure 10a displays the PL spectra of these thin films. It was found that more strikingly PL quenching effect is observed from CH 3 NH 3 PbI 3 :A 10 C 60 BHJ composite thin films than those pristine CH 3 NH 3 PbI 3 thin films, which indeed indicates that efficient electron extraction takes place in H 3 NH 3 PbI 3 :A 10 C 60 BHJ composite thin Graphical Abstract for the table of contents entry in a separate file： ： ： ： Colour graphic: maximum size 8 cm x 4 cm Text: one sentence, of maximum 20 words, highlighting the novelty of the work Bulk heterojunction device structure is invented to address the unbalanced charge carrier extraction efficiencies in perovskite hybrid solar cells. (19 wards)

Although great efforts have been devoted to enhancing the efficiency and stability of perovskite solar cells (PSCs), the performance of PSCs has been far lower than anticipated. Interface engineering is helpful for obtaining high efficiency and stability through control of the interfacial charge transfer in PSCs. This paper demonstrates that the efficiency and stability of PSCs can be enhanced by introducing stable α-CsPbI 3 quantum dots (QDs) as an interface layer between the perovskite film and the hole transport material (HTM) layer. By synergistically controlling the valence band position (VBP) of the perovskite and the interface layer, an interface engineering strategy was successfully used to increase the efficiency of hole transfer from the perovskite to the HTM layer, resulting in the power conversion efficiency increasing from 15.17 to 18.56%. In addition, the enhancement of the stability of PSCs can be attributed to coating inorganic CsPbI 3 QDs onto the perovskite layer, which have a high moisture stability and result in long-term stability of the PSCs in ambient air.

In this study, we report solution-processed photodetectors fabricated by methylammonium triiodide perovskite (CH 3 NH 3 PbI 3) incorporated with PbS quantum dots (QDs) through the trapassisted charge-injection effect. In order to increase the photo-responsivity by eliminating the charge injection barrier from the cathode electrode, PbS QDs, which possesses large amount of trap states, are introduced into the CH 3 NH 3 PbI 3 thin film for establishing ohmic contact at the CH 3 NH 3 PbI 3 /aluminum (Al) interface. As a result, an external quantum efficiency of ~4500 %, a photoresponsivity of ~15000 mA/W and a detectivity of over 6×10 13 Jones (1 Jones=1 cmHz 1/2 W-1) at a small bias of 2 volts, and a photoresponse time of 11.5 µs are observed from the solution-processed photodetectors fabricated by the CH 3 NH 3 PbI 3 :PbS QDs nanocomposites thin film.

Sensing from ultraviolet-visible to infrared is critical for both scientific and industrial applications. In this work, we demonstrate solution-processed ultrasensitive broad-band photodetectors (PDs) utilizing organolead halide perovskite materials (CH3NH3PbI3) and PbS quantum dots (QDs) as light harvesters. Through passivating the structural defects on the surface of PbS QDs with diminutive molecular-scaled CH3NH3PbI3, both trap states in the bandgap of PbS QDs for charge carrier recombination and the leakage currents occurring at the defect sites are significantly reduced. In addition, CH3NH3PbI3 itself is an excellent light harvester in photovoltaics, which contributes a great photoresponse in the ultraviolet-visible region. Consequently, operated at room temperature, the resultant PDs show a spectral response from 375 nm to 1100 nm, with high responsivities over 300 mA W(-1) and 130 mA W(-1), high detectivities exceeding 10(13) Jones (1 Jones = 1 cm Hz(1/2) W(-1)) and 5 × 10(12) Jones in the visible and near infrared regions, respectively. These device performance parameters are comparable to those from pristine inorganic counterparts. Thus, our results offer a facile and promising route for advancing the performance of broad-band PDs.

In this work, alcohol‐vapor solvent annealing treatment on CH3NH3PbI3 thin films is reported, aiming to improve the crystal growth and increase the grain size of the CH3NH3PbI3 crystal, thus boosting the performance of perovskite photovoltaics. By selectively controlling the CH3NH3I precursor, larger‐grain size, higher crystallinity, and pinhole‐free CH3NH3PbI3 thin films are realized, which result in enhanced charge carrier diffusion length, decreased charge carrier recombination, and suppressed dark currents. As a result, over 43% enhanced efficiency along with high reproducibility and eliminated photocurrent hysteresis behavior are observed from perovskite hybrid solar cells (pero‐HSCs) where the CH3NH3PbI3 thin films are treated by methanol vapor as compared with that of pristine pero‐HSCs where the CH3NH3PbI3 thin films are without any alcohol vapor treatment. In addition, the dramatically restrained dark currents and raised photocurrents give rise to over ten times enhanced detectivities for perovskite hybrid photodetectors, reaching over 1013 cm Hz1/2 W−1 (Jones) from 375 to 800 nm. These results demonstrate that the method provides a simple and facile way to boost the device performance of perovskite photovoltaics.

1.5–1.6 eV bandgap Pb‐based perovskite solar cells (PSCs) with 30–31% theoretical efficiency limit by the Shockley–Queisser model achieve 21–24% power conversion efficiencies (PCEs). However, the best PCEs of reported ideal‐bandgap (1.3–1.4 eV) Sn–Pb PSCs with a higher 33% theoretical efficiency limit are <18%, mainly because of their large open‐circuit voltage (Voc) deficits (>0.4 V). Herein, it is found that the addition of guanidinium bromide (GABr) can significantly improve the structural and photoelectric characteristics of ideal‐bandgap (≈1.34 eV) Sn–Pb perovskite films. GABr introduced in the perovskite films can efficiently reduce the high defect density caused by Sn2+ oxidation in the perovskite, which is favorable for facilitating hole transport, decreasing charge‐carrier recombination, and reducing the Voc deficit. Therefore, the best PCE of 20.63% with a certificated efficiency of 19.8% is achieved in 1.35 eV PSCs, along with a record small Voc deficit of 0.33 V, which is the highest PCE among all values reported to date for ideal‐bandgap Sn–Pb PSCs. Moreover, the GABr‐modified PSCs exhibit significantly improved environmental and thermal stability. This work represents a noteworthy step toward the fabrication of efficient and stable ideal‐bandgap PSCs.

developed silicon solar cells. It shows the great potential of PSCs as the dominator of next-generation photovoltaics. Whereas, during the evolution of PSC development, the metal oxide electron transporting layer (ETL), as well as the ETL/perovskite interface, [11][12][13][14] has always been an issue in regard to photovoltaic efficiency and device stability. [8] Derived from dye-sensitized solar cells (DSSCs), the combination of compact and mesoporous TiO 2 has been commonly utilized as ETLs during the early studies of PSCs. [15] But a high sintering temperature of ≈500 °C is normally required for the fabrication process, which is high energy consumption and incompatible with scalable depositions on flexible substrates. Worse still, TiO 2 is highly photocatalytic active under ultraviolet (UV) irradiation that severely hampers the long-term stability of PSCs under illumination. [16][17][18][19][20][21][22] Later on, a new ETL, SnO 2 , has been developed as a better candidate, due to its low-temperature processability [23] and high sustainability under UV illumination. [24][25][26][27] More importantly, SnO 2 film has superior crystallinity and carrier mobility in comparison to TiO 2 . [28,29] Thus, a single layer of compact SnO 2 could enable an efficient charge transport and suppressed recombination losses at the ETL/perovskite interface. Benefiting from these advantages, PSCs based on SnO 2 as ETL have reached PCE of 25.2% to date. [30] Whereas, considerable amount of oxygen vacancies on the SnO 2 surface would act as deep traps to capture the photogenerated carriers, which causes hysteresis and instability of the device. [31][32][33][34] And this intrinsic defect of SnO 2 needs to be resolved for a further PCE breakthrough of PSCs.In recent years, significant attempts of defect-passivation have been made to decrease the oxygen vacancies and trap states on SnO 2 surface. [35][36][37][38] Among them, n-type fullerene derivatives represent one of the most studied and efficacious passivator, [39][40][41][42] due to the ease of forming coordinate bonds between carboxylate group and SnO 2 surface. In addition, fullerene derivative is a common electron acceptor in organic solar cells (OSCs), [43] which grants an effective electron extraction from the perovskite active layer to ETL, thus contributing to higher PSC performances. Nevertheless, it should be noticed that π-cage structures of fullerene derivatives are prone to self-aggregate, [44] which strongly affects the validity and SnO 2 has been universally applied as electron transporting layer (ETL) towards the fabrication of highly efficient perovskite solar cells (PSCs), owing to its unique advantages including low-temperature solution-processability, high optical, transmittance and good electrical conductivity. Uncoordinated Sn-dangling bonds on SnO 2 surface exist as deep traps to capture the photogenerated carriers, causing hysteresis and device instability. Fullerene derivatives, though being widely utilized as the passivator for SnO 2 , are highly prone to...