| Organic-inorganic hybrid perovskite solar cells(PSCs)has attracted more and more attention.For all kind of PSCs the key issues to wholescale industrialization are always the improvement of its PCE and reducement of the cost.Therefor,the hotspots in perovskite solar research are expensive material replacement,new interfacial material developing and morphology and crystallinity control of perovskite layer.Simultaneously,a fast,stable and multi-angle PCE test system is desperate needed for developing new PSCs structures.Therefor we focused on these htspots and carried out the following works:(1)Virtual Instrument Technology has been applied in automatic test system design for PSCs.With the IEEE-488 as main bus,we connect PC,Solar simulator and kelith 2400 to form a long-range(up to 20m),wide band and high stability hardware system.Then we programed 3 testing software(known as vi)with LabVIEW 2014.Among them,the J-V curve forward scan vi is designed for fast testing and curve drafting for newly assembled solar cells,which can provide a preliminary judgment on the new structure or materials we used.Then,the J-V Curve Circular scan vi will provide complete and thorough evaluation of the device's detailed photovoltaic performance.The stability of the device is tested by measuring the solar cell device with a changing bias in both reverse and forward scan.Also,we can determine the J-V hysteresis for the device by compare the two curves of reverse and forward scan.Last,the time/current recording vi is designed to record the device status when working at its maximum output power.By calculating PCE from this curve and compared with PCE from the Circular J-V Curve we can get further proof on the accuracy.(2)We propose an assemble process for classic structure PSCs applicable in our lab which including synthesis and purification of CH3NH3 I,surface etching for ITO substrate.Finally the single-substrate champion device based on structure ITO/PEDOT:PSS/ CH3NH3PbI3/PC71BM/Al possessed PCE of 6 %.(3)The hole transport material(HTM)of PSCs response for bearing perovskite layer,combine ITO substrate,provide thickness and isolate recombination.Based on the process propsed,we use conductive graphite as the main material,by adding carbon black and additives such as ZrO2,we prepared a stable structure of graphite/carbon black/ZrO2 composite carbon electrodes.Then we fabricated monolithic devices with carbon counter electrode and used CH3NH3PbI3 as light absorber.After compared four kinds of solvents we have the reliable conclusion that DMF is best precursor solvent.Then we used nanorod form TiO2 as additional host of CH3NH3PbI3,and reach a PCE of 9.54%.(4)Finally,we demonstrate low-temperature solution-processed inorganic p-type vanadium oxide(VOx)as the HTL in planarheterojunction PSCs.Melt-quenching technique was applied to synthesis VOx collosol which would coordinate with spin-coating.The value of x in VOx was estimated to be 2.428 by X-ray photoelectron spectroscopy(XPS).The influence of different annealing temperature on VOx oxide layer were characterized by transmission spectra and work function test.To further compare VOx and PEDOT:PSS as HTM,the Steady-state PL spectra was carried out.The influence of different sipn-coating speed on VOx was also studied for optimizing PCE.It has been reported that it is a challenge for Organometal trihalide perovskite(OTP)absorbers to attain high-percentage surface coverage on VOx layers,so we developed a solvent-assisted process for the deposition of CH3NH3PbI3 thin films on VOx coated substrates.During the spin-coating process,an orthogonal solvent of toluene was applied to quenchthe wet film.Attributing to the hydrophilic surface of the VOx layer,a perovskite thin film with high percentage coverage formed.Upon optimization,a champion device showing a PCE of over 14% was fabricated.Almost no hysteresis phenomenon can be observed in this VOx based device,showing a PCE of 14.23% for reverse scan and 14.14% for forward scan. |
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