Display omitted
•Ionic liquids (ILs) aided-device engineering champions is widely reviewed.•The role of ILs in the production of high-quality perovskite film is discussed.•ILs can potentially improve ...the long-term stability of perovskite solar cells.•ILs represents a significant step toward reliable perovskite PV technology.
The efficiency of perovskite solar cells (PSCs) is rapidly increasing, so that their long-term operational stability has become a major focus for commercialization and market adoption. The development of novel strategies and materials to improve the stability of small and large solar modules without compromising power conversion efficiency (PCE) is an ongoing challenge. Ionic liquids (ILs) are emerging as useful additives, solvents, and charge transport materials for the preparation of highly efficient perovskite films. Perovskite crystallizes slowly in ILs to form large and uniform grains, and PSCs fabricated with high-quality perovskite films are efficient and stable. Herein we review recently developed systemic device engineering, and we discuss the impact of ILs in the production of highly efficient and stable PSCs. This review is intended to serve as a guide to develop highly crystalline perovskite films with larger grains and more homogeneous morphologies, all of which contribute to enhancing the stability of PSC performance. Recent progress in the use of ILs as solvents and additives for PSCs is a significant step toward developing reliable perovskite photovoltaic devices. Finally, we discuss challenges and future research directions for the fabrication of efficient and stable PSCs.
Interface engineering plays a promising strategy to produce highly efficient planar heterojunction (PHJ) perovskite solar cells. The deep trap states on the compact-TiOx surface leading to a large ...leakage current and recombination of charge carriers. To solve the problems, interfacial engineering of electron collecting layer (ECL) compact-TiOx by a thin-layer of one-step solution-processed and low-cost organic material is applied. In contrast, commonly used PCBM is still expensive material. Herein, a new, low-temperature processable higher potential of 60fulleropyrrolidine derivatives named as N-phenyl60fulleropyrrolidines (PNP) was introduced as an interfacial modification of ECL compact-TiOx with the varying thickness of 10, 20, and 30nm to replace the commonly used PCBM in PHJ perovskite solar cells. The modified surface morphology was achieved by introducing PNP interfacial layers that enhanced the surface-energy properties of the cells in terms of enhanced photocurrent. Compared with PCBM, PNP features a higher electronic mobility and stronger hydrophobic nature. The enhancement of power conversion efficiency was obtained from 5.12% to 8.23%, with an increase in short-circuit current density (Jsc) from 11.90 to 21.44mAcm−2 and fill factor (FF) from 0.49 to 0.56 owing to insertion of optimum 10-nm-thickness PNP that led to more efficient electron transport and charge extraction in the solar cell performances. The present work provides an important sign in the aspects to the low-cost mass production of perovskite solar cells.
Display omitted
•A new design, low-temperature processable higher potential of N-phenyl60fulleropyrrolidines (PNP) was introduced as an interfacial modification of electron collecting layer amorphous compact-TiOx.•Investigate the effect upon the varying thickness of PNP interfacial layer on the resulting device performances.•The optimized morphology obtained by surface-energy modification enhanced the photocurrent of the corresponding solar cell.•Charge transfer was efficiently enhanced using insertion of PNP between the perovskite and amorphous compact-TiOx layer.
Perovskite solar cells (PSCs) have appeared as a promising design for next-generation thin-film photovoltaics because of their cost-efficient fabrication processes and excellent optoelectronic ...properties. However, PSCs containing a metal oxide compact layer (CL) suffer from poor long-term stability and performance. The quality of the underlying substrate strongly influences the growth of the perovskite layer. In turn, the perovskite film quality directly affects the efficiency and stability of the resultant PSCs. Thus, substrate modification with metal oxide CLs to produce highly efficient and stable PSCs has drawn attention. In this review, metal oxide-based electron transport layers (ETLs) used in PSCs and their systemic modification are reviewed. The roles of ETLs in the design and fabrication of efficient and stable PSCs are also discussed. This review will guide the further development of perovskite films with larger grains, higher crystallinity, and more homogeneous morphology, which correlate to higher stable PSC performance. The challenges and future research directions for PSCs containing compact ETLs are also described with the goal of improving their sustainability to reach new heights of clean energy production.
The performance of organic photovoltaic (OPV) cells has considerably improved over the past decade, and now exceeds an energy conversion efficiency of 10%, the benchmark for practical use. One factor ...contributing to this increase is the development of π-conjugated linear acceptor molecules as alternatives to fullerene derivatives. Although conversion efficiency is an important issue for practical applications, device stability is also necessary for commercialization of OPV technologies. To date, long-term stability has been examined in OPV devices based on fullerenes. However, the factors involved in performance degradation remain poorly understood. It is difficult to address this problem because of the multilayer nature of the devices and many factors involved in degradation. In recent OPV devices based on π-conjugated molecules as acceptors, there have been few reports on stability under continuous light irradiation. Ensuring the stability of the π-conjugated molecules under illumination and electrical operation is critical for achieving practical use of OPV devices. In this paper, we comprehensively analyzed OPV devices based on EH-IDTBR as an acceptor material. We identified a decrease in OPV performance of approximately 50% under 100-h light irradiation, which we attribute to increased resistance of the organic semiconductor layer. The increase in resistance was caused by a decrease in the number of carriers, suggesting that structural changes in the EH-IDTBR molecule are an important factor affecting degradation.
Display omitted
Detailed analyses of the microstructures of bulk-heterojunction (BHJ) layers are important for the development of high-performance photovoltaic organic solar cells (OSCs). However, analytical methods ...for BHJ layer microstructures are limited because BHJ films are composed of a complex mixture of donor and acceptor materials. In our previous study on the microstructure of a BHJ film composed of donor polymers and fullerene-based acceptors, we analyzed donor polymer-only films after selectively extracting fullerene-based acceptors from the film by atomic force microscopy (AFM). Not only was AFM suitable for a clear analysis of the morphology of the donor polymers in the BHJ film, but it also allowed us to approximate the acceptor morphology by analyzing the pores in the extracted films. Herein we report a method for the selective extraction of nonfullerene acceptors (NFAs) from a BHJ layer in OSCs and provide a detailed analysis of the remaining BHJ films based upon AFM. We found that butyl glycidyl ether is an effective solvent to extract NFAs from BHJ films without damaging the donor polymer films. By using the selective extraction method, the morphologies of NFA-free BHJ films fabricated under various conditions were studied in detail. The results may be useful for the optimization of BHJ film structures composed of NFAs and donor polymers.
Chemical bath deposited titanium oxide (TiO
x
) as an electron collection layer is introduced between the organic layer and the indium tin oxide (ITO) electrode for improving the performance of ...inverted bulk-heterojunction organic thin film solar cells with 1
cm
2 active area, where regioregular poly(3-hexylthiophene) (P3HT) and 6,6-phenyl C
61 butyric acid methyl ester (PCBM) were mainly used as the photo-active layer. The uniform and thin TiO
x
film was easily prepared onto the ITO electrode in air by simple chemical bath deposition method. The cell performance was almost maintained in an ambient atmosphere under continuous light irradiation of 100
h despite non-sealing. The cell with bulk-heterojunction organic thin film consisted of 6.6 diphenyl C
62 bis(butyric acid methyl ester) (bis-PCBM) and P3HT prepared under best condition showed the power conversion efficiency (PCE) of 3.8% under the AM1.5G simulated sunlight.
Here, we reported that a new carbon electrode prepared with an activated carbon was superior to a Pt sputtered electrode as the counter electrode of dye-sensitized solar cells. The photovoltaic ...performance was largely influenced by the roughness factor of carbon electrode. The open-circuit voltage increased by about 60
mV using the carbon counter electrode compared to the Pt counter electrode because of positive shift of the formal potential for I
3
−/I
− couple.
An indium tin oxide/titanium oxide/6,6-phenyl C
61 butyric acid methyl ester:regioregular poly(3-hexylthiophene)/poly(3,4-ethylenedioxylenethiophene):poly(4-styrene sulfonic acid)/Au type organic ...solar cell (ITO/TiO
x
/PCBM:P3HT/PEDOT:PSS/Au) with 1
cm
2 active area, which is called “inverted-type solar cell”, was developed using an ITO/amorphous titanium oxide (TiO
x
) electrode prepared by a sol–gel technique instead of a low functional electrode such as Al. The power conversion efficiency (
η) of 2.47% was obtained by irradiating AM 1.5G-100
mW
cm
−2 simulated sunlight. We found that a photoconduction of TiO
x
by irradiating UV light containing slightly in the simulated sunlight was required to drive this solar cell. The device durability in an ambient atmosphere was maintained for more than 20
h under continuous light irradiation. Further, when the air-stable device was covered by a glass plate with a water getter sheet which was coated by an epoxy-UV resin as sealing material, the durability was still higher and over 96% of relative efficiency was observed even after continuous light irradiation for 120
h.
We developed an inverted type bulk-heterojunction organic solar cell with 1 cm
2 active area using a fluorine-doped tin oxide/electrodeposited amorphous (TiO
x
) or anatase (TiO
2) titanium oxide ...electrode instead of the low work-functional electrode such as Al. The cell with TiO
2 showed the power conversion efficiency (
η) of 2.5% by irradiating AM 1.5–100 mW cm
−
2
simulated sunlight. While, the performance of the cell with TiO
x
was almost maintained in an ambient atmosphere under continuous light irradiation of 10 h, although slightly small initial
η value of 2.1% was observed.
Photoelectrochemical oxidation of thiols was enhanced with a threshold potential of −0.35 V
vs.
Ag/AgCl by the use of a ZnPc/PCBM:P3HT/ZnO electode, which was prepared by removing the PEDOT:PSS/Au ...electrode of an inverted OPV device and coating it with ZnPc. A co-photocatalysis property of ZnPc was observed in the photoelectrochemistry and scanning Kelvin probe microscopy.
Photoelectrochemical oxidation of thiols was enhanced with a threshold potential of −0.35 V
vs.
Ag/AgCl by a ZnPc/PCBM:P3HT/ZnO electode, which was prepared by removing the PEDOT:PSS/Au electrode of an inverted OPV device and coating it with ZnPc.
PDF
