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An antireflective coating made by TiO 2 nanocone array is designed on an ultrathin multilayer GaAs substrate (the thickness of GaAs is 300 nm). The intrinsic light trapping, carrier recombination and photoconversion are simulated by a complete photoelectric simulation. The results show that the optimized light trapping design can enhance the electromagnetic resonance in active layer and lead to an extraordinary enhancement of both absorption and power conversion capabilities in GaAs solar cell. The short-circuit current density increases by 51.12%, from 12.01 mA/cm2 to 18.15 mA/cm2 and power conversion efficiency increases by 52.83%, from 11.00% to 16.81% compared to the reference benchmark. [ABSTRACT FROM AUTHOR]

Abstract Although the PbCl 2 has been exploited to improve the performance of perovskite solar cells, the mechanism of enhancement by the introducing PbCl 2 is not fully understudied. In present work, we used the PbCl 2 as a dopant to improve the perovskite film quality, we found the crystalline and grain size of perovskite film both increased with 10% molar ratio of PbCl 2. The in situ time-resolved grazing incidence wide-angle X-ray scattering measurements revealed that more pre-nucleated suspended in the solution when employed the PbCl 2 dopant, leading to high crystalline for perovskite film. An incorporation of the space charge limit current, photoluminescence, time-resolved photoluminescence measurements, we uncover the function of PbCl 2 in reduced trap density, decreased charge recombination and enhanced carrier lifetime. As a result, the efficiency of planar-structure perovskite solar cells based on PbCl 2 enhanced to as high as 19.79% with reduced hysteresis, increased by ∼23% compared to the device without PbCl 2 (16.05%). We believe that this work would provide a fundamental prospective for mixed perovskite and promote its application in perovskite photovoltaics. Graphical abstract Image 1 Highlights • The efficiency of planar perovskite solar cell reaches to 19.79% using PbCl 2 doping, and the mechanism of PbCl 2 function are systemically investigated. • The perovskite film with PbCl 2 doping exhibits good crystalline, large grains, full surface coverage and pin-hole free. • The effect of PbCl 2 doped significantly suppresses charge recombination and promotes the carriers transfer. [ABSTRACT FROM AUTHOR]

A dielectric fishnet nanostructure is designed to increase the light trapping capability of ultra-thin solar cells. The complex performance of ultra-thin cells such as the optical response and electrical response are fully quantified in simulation through a complete optoelectronic investigation. The results show that the optimized light trapping nanostructure can enhances the electromagnetic resonance in active layer then lead to extraordinary enhancement of both absorption and light-conversion capabilities in the solar cell. The short-circuit current density increases by 49.46% from 9.40 mA/cm 2 to 14.05 mA/cm 2 and light-conversion efficiency increases by 51.84% from 9.51% to 14.44% compared to the benchmark, a solar cell with an ITO-GaAs-Ag structure. [ABSTRACT FROM AUTHOR]

Inverted perovskite solar cells have attracted a great deal of attention due to its high power conversion efficiency, simple configuration, and low-cost processing. The hole transport material (HTM) is a crucial factor in high performance inverted perovskite solar cell. However, the hole mobility for most common of HTM is too low to matching perovskite materials. Herein, we report a superior HTM with high hole mobility to significantly improve solar cell efficiency. Upon doing the commonly used PEDOT:PSS HTM by graphene oxide (GO), its hole mobility is increased from 5.55 × 10 −5 to 1.57 × 10 −4 cm 2 V −1 s −1 , leading to efficient hole extraction and low current leakage, therefore 20% higher power conversion efficiency comparing to the control device without the GO doping. The development open the opportunities for efficient HTMs based on the two-dimensional materials in the perovskite solar cells. [ABSTRACT FROM AUTHOR]

• A complex gradient passivation strategy was first proposed for inverted PSCs. • In(SCN 2 H 4) 3 Cl 3 effectively passivates defect states in bulk perovskite layer. • In(SCN 2 H 4) 3 Cl 3 facilitates hole extraction by modulating interface energy level alignment. • The efficiency and stability of inverted PSCs are significantly improved. To address the interfacial and bulk defects and mismatched energy band alignment at perovskite/hole transport layr (HTL) interface in inverted perovskite solar cells (PSCs), here a novel In(SCN 2 H 4) 3 Cl 3 complex diffusion doping strategy was proposed to construct CH 3 NH 3 PbI 3 :In(SCN 2 H 4) 3 Cl 3 composite layer for poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA)-based inverted PSCs. The In(tu) 3 Cl 3 effectively promotes the quality of perovskite films with larger perovskite crystal grains and flatter and denser surfaces. Both theoretical and experimental results reveal that the In(SCN 2 H 4) 3 Cl 3 can not only passivate interfacial and bulk defects in perovskite layer, but also form a spatial separation of photogenerated charges through CH 3 NH 3 PbI 3 :In(SCN 2 H 4) 3 Cl 3 heterojunction interface, which effectively decreases the charge recombination and enhances charge separation and transport property in PSCs. Moreover, the In(SCN 2 H 4) 3 Cl 3 optimizes energy band alignment at perovskite/PTAA interface and creates a polarization electric field at the PTAA/In(SCN 2 H 4) 3 Cl 3 interface directing toward PTAA layer, which promotes the hole transfer from the CH 3 NH 3 PbI 3 to the PTAA and increases the open-circuit voltage (V oc). As a consequence, optimized inverted PSCs with CH 3 NH 3 PbI 3 :In(SCN 2 H 4) 3 Cl 3 layer achieve high efficiency of 21.25 % and also show a significantly improved long-term stability under different aging test conditions. Our work provides a valuable guide for designing efficient and stable inverted PSCs. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is widely used as an interfacial material in applications such as organic light emitting diodes and photovoltaic devices. Herein we report a layer-by-layer (LbL) assembled GO thin film as an anode interfacial layer (AIL) for efficient polymer solar cells (PSCs). The GO thin film is fabricated by alternately depositing cationic polyelectrolyte poly(diallyldimethylammonium chloride) (PDDA) and GO on ITO/glass substrate, which possesses controllable thickness by adjusting LbL deposition frequency. The presence of ultrathin GO films improves the work function of ITO, leading to a better contact between the active layer and ITO anode. With the optimized number of deposition times, the efficiency of 6.04% for the PSC with PDDA-GO bilayer (GO-2) as the AIL was achieved. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the effects of interfacial modification on the performance of the inverted hybrid solar cells consisting of P3HT as an electron donor and CdS nanoporous film as an electron acceptor. The device performance can be enhanced by grafting N719 dye molecules onto the surface of CdS. By optimizing the P3HT thickness, the power conversion efficiency (PCE) of the CdS/N719/P3HT hybrid solar cell is increased to 1.06% from 0.06% of the CdS/P3HT hybrid solar cell, with a champion device efficiency of 1.31% under AM1.5G of 100mW/cm2 intensity. It is revealed that the interface modification by N719 dye can promote exciton dissociation between the two components, reduce interfacial charge recombination, and form a dipole layer at the interface that modulated the interface energy level, which enhances the open circuit voltage and short circuit current coinstantaneously. This work may provide a general method to achieve high performance organic–inorganic hybrid solar cells by interfacial modification. [Copyright &y& Elsevier]

The effect of transparent conductive oxide (TCO) on the performance of compact-layer free perovskite solar cells has been investigated. The results show that the perovskite film formation, charge transfer and charge recombination are affected by the TCO layer. All common TCOs, including ITO, FTO and AZO, show some beneficial and detrimental characters for solar cell application. Finally, the compact-layer free perovskite solar cells based on them show similar performance. [ABSTRACT FROM AUTHOR]

High quality CH 3 NH 3 PbI (3-x) Br x perovskite film with full surface coverage and fewer trap states was prepared using a single-step deposition process and PbBr 2 doped perovskite precursor solution. Specifically, the thin film surface becomes rougher and the grain size gets larger as the PbBr 2 concentration was increased from 1% to 10 mol%. Ultraviolet–visible spectroscopy (UV–vis) and incident photon-to-current efficiency (IPCE) spectra show that abnormal absorption onset shifts to longer wavelength with increasing the content of PbBr 2 , because the larger grain size can reduce the stress accumulated in the lattice over the Pb–I bond angle. It is surprising to see that when 5 mol% of PbBr 2 was used, the CH 3 NH 3 PbI 3 (MAPbI 3) shows the best thermal stability, with the decomposition onset increased by about 20 °C. The photoluminescence (PL) peak of the CH 3 NH 3 PbI (3-x) Br x film shifts to smaller wavelength as more PbBr 2 was used owing to decreased trap states in perovskite films. It is found that at the optimal PbBr 2 content of 5 mol%, the CH 3 NH 3 PbI (3-x) Br x based solar cell gives open-circuit voltage of 1.08 V with power conversion efficiency (PCE) as high as 18.97%, about 16.6% higher than the device based on the MAPbI 3 without Br. • Abnormal absorption onset shift of CH 3 NH 3 PbI 3 film by adding PbBr 2. • Enhancement the crystalline quality and grain size of the CH 3 NH 3 PbI (3-x) Br x film. • The highest PCE of CH 3 NH 3 PbI (3-x) Br x perovskite solar cell is 18.97%. [ABSTRACT FROM AUTHOR]

Highlights • Absorption layer plays a very important role in the performance of perovskite solar cells. • We calculated the defect state density and carrier mobility of the device under dark current. • The FAPbI 3 solar cells show superior performance compared to the MAPbI 3 -based devices. Abstract Absorption layer plays a very important role in the high efficiency and stability perovskite solar cells, there have been many reports that based on CH 3 NH 3 PbI 3 (MAPbI 3) and NH 2 CH NH 2 PbI 3 (FAPbI 3) perovskite solar cells, but the system compares the performance differences between MAPbI 3 -based and FAPbI 3 -based perovskite solar cells. The MAPbI 3 and FAPbI 3 perovskite solar cells are differences in topography, optical performance, the performance of solar cells, and device stability. It is particularly noteworthy that we calculated the defect state density and carrier mobility of the device under dark current. Through the construction of the solar cells, it has been found that the planar FAPbI 3 perovskite solar cells have better photoelectric conversion efficiency. The FAPbI 3 solar cells show superior performance compared to the MAPbI 3 -based devices, the power conversion efficiency of 16.38% and 18.61% was obtained with high short circuit current density of 21.11 and 23.18 mA/cm2. [ABSTRACT FROM AUTHOR]

The low temperature-processed electron transport layers are crucial to the commercial perovskite solar cells (PSCs). PC 60 BM/SnO 2 bilayer electron transport layer (ETL) has gradually been reported, but the mechanism of enhancement by the introducing PC 60 BM on SnO 2 is not fully understudied. In this work, low temperature PC 60 BM/SnO 2 bilayer ETLs are successfully prepared via a solution process. The introduction of PC 60 BM dramatically enhances the performance of the planar PSCs, and the reason has been systemically investigated. The results show that the existence of PC 60 BM could enhance the crystalline quality and grain boundary integration in perovskite films. The J-V analysis, absorption spectra, photoluminescence spectra and time-resolved photoluminescence spectra show that both the light harvesting of perovskite films and carrier extraction from perovskite films to PC 60 BM/SnO 2 bilayer have been enhanced. Otherwise, perovskite films on ITO/SnO 2 /PC 60 BM substrate have a lower trap state density and higher electron mobility than those of ITO/SnO 2 substrate or bare ITO substrate. All the results suggest that low temperature-processed PC 60 BM/SnO 2 ETLs will benefit the performance of PSCs and promote the commercial application of planar PSCs. [ABSTRACT FROM AUTHOR]

The light trapping performance of Si nanowire with different inclination angles were systematically studied by COMSOL Multiphysics. The inclined nanowires with inclination angles smaller than 60° show greater light trapping ability than their counterparts of the vertical nanowires. The Si solar cell with the inclined nanowires of the optimal parameters, whose θ =30°, P =400 nm, D =140 nm, can achieve a 32.395 mA/cm 2 short circuit photocurrent density and a 35.655% conversion efficiency. The study of the inclined nanowire provides an effective way for further utilization of the incoming light. [ABSTRACT FROM AUTHOR]

[Display omitted] • The stable α-phase pure FAPbI 3 is prepared by imidazolium-based ionic liquid. • The efficiency enhances to 20.76% due to the high properties of pure FAPbI 3. • The unencapsulated pure FAPbI 3 devices show the excellent stability. The stable black α-phase is the key to attaining high-efficiency formamidinium lead triiodide (FAPbI 3) perovskite solar cells (PSCs). There have been some reports using different sizes of ions to stabilize α-phase FAPbI 3 ; unfortunately, they often affect the bandgap, stability and carrier dynamics, in addition to increasing the number of carrier trap sites. Herein, we present 1-allyl-3-methylimidazolium-chloride (AMICl) ionic liquid to stabilize the α-phase of pure FAPbI 3 perovskite without encountering the above adversities. It is found that the thermodynamic temperature of α-FAPbI 3 is significantly reduced from 150 °C to 145 °C by using AMICl, and the absorption edge of FAPbI 3 remains at 850 nm. The efficiency of a FAPbI 3 device with AMICl is increased from 18.47% for the control device to 20.76%, one of the highest values among pure FAPbI 3 solar cells. The high efficiency is attributed to the low trap density, long carrier lifetime and suppressed carrier recombination, thanks to the large grain size and good crystallinity of FAPbI 3 generated by the formation of intermediate products from PbI 2 and AMICl, demonstrating by density functional theory (DFT) calculation. Meanwhile, FAPbI 3 solar cells with AMICl exhibit the excellent environmental stability. The bare device without any encapsulation maintains about 87% of its initial value after being exposed to ambient for 24 days, significantly improved over the control device, which retains about 53% of its initial efficiency under the same conditions. [ABSTRACT FROM AUTHOR]