Marko Jošt

University of Ljubljana · Faculty of Electrical Engineering

Improving the power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs) remain the two most important goals of perovskite research. Herein, the effects of Al 2 O 3 interlayer on the performance of formamidinium‐cesiums and “triple cation” PSCs by depositing a thin Al 2 O 3 layer via atomic layer deposition on different interf...

Perovskite‐based solar cells exhibit peculiar outdoor performance which is not yet fully understood. The results of outdoor tests may contain hidden, but valuable information that cannot be fully extracted from measurements alone. One such phenomenon is the effect of nighttime degradation and the subsequent light‐soaking recovery, which can take fr...

Indoor photovoltaics (IPV) hold enormous market potential driven by the rising demand for perpetual energy sources to power various small electrical devices and especially Internet of things (IoT) devices. Perovskite solar cells (PSCs) offer exciting prospects for this role. This study sets out to deepen our knowledge of PSC performance under reali...

The ongoing development of photovoltaics into terawatt scale poses a number of challenges where the optics and photonics communities can contribute. An international consortium recently compiled a roadmap that elaborates on these challenges.

In this study, we present a development of a solar-powered Internet-of-Things (IoT) device, that incorporates both light energy harvesting and solar cell monitoring, which we demonstrate by long term monitoring of a single perovskite solar cell in office-like indoor environment. Using off-the-shelf components we engineered a compact, self-sufficien...

A comprehensive algorithm for calculating the energy yield (EY) is used as the most important figure‐of‐merit in determining the capabilities of PV devices in realistic operation. The model is based on advanced optical modeling and extensive opto‐thermo‐electrical characterization. It takes the realistic environmental and device installation data f...

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a very versatile surface-sensitive mass spectrometry method regarding the type of data that can be acquired. Measuring mass survey spectra, we analyse the sample surface and determine different ions through their m/z values as well as their intensities. SIMS depth profiles offer us the po...

We demonstrate a monolithic perovskite/CIGS tandem solar cell with a certified power conversion efficiency (PCE) of 24.2%. The tandem solar cell still exhibits photocurrent mismatch between the subcells; thus optical simulations are used to determine the optimal device stack. Results reveal a high optical potential with the optimized device reachin...

Accurate forecasting of yearly energy yield of photovoltaic devices under realistic operating conditions is key for numerous practical applications related to further evolution of photovoltaics. In this work we present development and validation of an energy yield model applied to planar perovskite solar cells. The model is based on the combination...

Potential induced degradation (PID) is a solar cell related degradation mechanism due to high potential difference in a photovoltaic (PV) module between the solar cells and its grounded frame. This type of degradation is well known for silicon PV, however, for perovskites it has not been thoroughly researched yet. Here, we investigate the PID of pe...

In monolithic tandem solar cells, current-voltage (J-V) characteristics of subcells provide invaluable information about their quality and tandem operation. However, accessing the subcell J-Vs is challenging and requires sophisticated spectral methods. In this letter, we present a customised, bichromatic LED setup (BCLED) for in-depth analysis of t...

Monolithic perovskite/silicon tandem solar cells recently surpassed the efficiency of silicon single‐junction solar cells. Most tandem cells utilize >250 µm thick, planarized float‐zone (FZ) silicon, which is not compatible with commercial production using <200 µm thick Czochralski (CZ) silicon. We demonstrate perovskite/silicon tandem cells based...

Efficiency from hole-selective contacts Perovskite/silicon tandem solar cells must stabilize a perovskite material with a wide bandgap and also maintain efficient charge carrier transport. Al-Ashouri et al. stabilized a perovskite with a 1.68–electron volt bandgap with a self-assembled monolayer that acted as an efficient hole-selective contact tha...

For methylammonium lead iodide perovskite solar cells prepared by co-evaporation, power conversion efficiencies of over 20% have been already demonstrated, however, so far only in n-i-p configuration. Currently, the overall major challenges are the complex evaporation characteristics of organic precursors that strongly depend on the underlying char...

Perovskite solar cells (PSC) have shown that under laboratory conditions they can compete with established photovoltaic technologies. However, controlled laboratory measurements usually performed do not fully resemble operational conditions and field testing outdoors, with day‐night cycles, changing irradiance and temperature. In this contribution,...

Tandem solar cells are the next step in the photovoltaic (PV) evolution due to their higher power conversion efficiency (PCE) potential than currently dominating, but inherently limited, single‐junction solar cells. With the emergence of metal halide perovskite absorber materials, the fabrication of highly efficient tandem solar cells, at a reasona...

Monolithic [Cs0.05(MA0.17FA0.83)0.95]Pb(I0.83Br0.17)3/Cu(In,Ga)Se2 (perovskite/CIGS) tandem solar cells promise high performance and can be processed on flexible substrates, enabling cost-efficient and ultra-lightweight space photovoltaics with power-to-weight and power-to-cost ratios surpassing those of state-of-the-art III-V semiconductor-based m...

The rapid rise of perovskite solar cells (PSCs) is increasingly limited by the available charge-selective contacts. This work introduces two new hole-selective contacts for p–i–n PSCs that outperform all typical p-contacts in versatility, scalability and PSC power-conversion efficiency (PCE). The molecules are based on carbazole bodies with phospho...

Low-temperature atomic layer deposition (ALD) offers significant merits in terms of processing uniform, conformal and pinhole-free thin films, with sub-nanometer thickness control. In this work, plasma-assisted atomic layer deposition (ALD) of nickel oxide (NiO) is carried out by adopting bis-methylcyclopentadienyl-nickel (Ni(MeCp)2) as precursor a...

The effect of sodium doping in NiO as a contact layer for perovskite solar cells is investigated. A combined X‐ray diffraction and X‐ray photoelectron spectroscopy analysis reveals that Na+ mostly segregates as NaOx/NaCl species around NiO crystallites, with the effect of reducing interface capacitance as revealed by impedance spectroscopy. Inspire...

Determination of the device performance parameters of perovskite solar cells is far from trivial as transient effects may cause large discrepancies in current-voltage measurements as a function of scan rate and pre-conditioning. Maximum power point tracking, MPPT, enables to determine the steady-state maximum power conversion efficiency. However, t...

Metal halide perovskites show great promise to enable highly efficient and low cost tandem solar cells when being combined with silicon. Here, we combine rear junction silicon heterojunction bottom cells with p-i-n perovskite top cells into highly efficient monolithic tandem solar cells with a certified power conversion efficiency (PCE) of 25.0 %....

Highly efficient perovskite based solar cells have the potential to be a game-changing solar array technology for space applications that can be flexible, truly roll-able, ultra-lightweight and highly stowable. Outside earth’s magnetic field, however, ionizing radiation causes localized defect states that accumulate and ultimately cause the failure...

The structural phases and optoelectronic properties of coevaporated CsPbI3 thin films with a wide range of [CsI]/[PbI2] compositional ratios are investigated using high throughput experimentation and gradient samples. It is found that for CsI‐rich growth conditions, CsPbI3 can be synthesized directly at low temperature into the distorted perovskite...

Combining the emerging perovskite solar cell technology with existing silicon approaches in a tandem cell design offers the possibility for new low-cost high-performance devices. In this study, the potential of liquid phase crystallized silicon (LPC-Si) solar cells as a bottom cell in an all-thin-film tandem device is investigated. By optimizing th...

Perovskite-based tandem solar cells can increase the power conversion efficiency (PCE) of conventional single-junction photovoltaic devices. Here, we present monolithic perovskite/CIGSe tandem solar cells with a perovskite top cell fabricated directly on an as-grown, rough CIGSe bottom cell. To prevent potential shunting due to the rough CIGSe surf...

Efficient light management in monolithic perovskite/silicon tandem solar cells is one of the prerequisites for achieving high power conversion efficiencies (PCEs). Textured silicon wafers can be utilized for light management, however, this is typically not compatible with perovskite solution processing. Here, we instead employ a textured light mana...

Perovskite/silicon tandem solar cells are the most promising concept for a future photovoltaic technology. We report on recent progress from an optical viewpoint and disucss how we achieved more than 25% device efficiency.

In article number 1801892, Steve Albrecht, Vytautas Getautis and co‐workers demonstrate a novel promising concept for the formation of a hole selective monolayer in perovskite solar cells. A low temperature dopant‐free technique makes it suitable for different substrates.

The unprecedented emergence of perovskite‐based solar cells (PSCs) has been accompanied by an intensive search of suitable materials for charge‐selective contacts. For the first time a hole‐transporting self‐assembled monolayer (SAM) as the dopant‐free hole‐selective contact in p–i–n PSCs is used and a power conversion efficiency of up to 17.8% wit...

Laser-based patterning for monolithic serial interconnection of metal halide perovskite (MHP) solar cells is a key process for industrial manufacturing of large-scale MHP solar panels. It requires reliable patterning process parameters to achieve low interconnection losses and, thus, high efficiencies. Here, P2 laser patterning of the perovskite la...

We report on the formation of wrinkle-patterned surface morphologies in cesium formamidinium based CsxFA1-xPb(I1-yBry)3 perovskite compositions with x = 0–0.3 and y = 0–0.3 under various spin-coating conditions. By varying the Cs and Br content, perovskite precursor solution concentration, and spin-coating procedure, the occurrence and characterist...

We performed optical simulations using hydrogenated nanocrystalline silicon oxide (nc-SiOx:H) as n-doped interlayer in monolithic perovskite/c-Si heterojunction tandem solar cells. Depending on the adjustable value of its refractive index (2.0 – 2.7) and thickness, nc-SiOx:H allows to optically manage the infrared light absorption in the c-Si botto...

Inorganic-organic perovskites like methylammonium-lead-iodide have proven to be an effective class of materials for fabricating efficient solar cells. To improve their performance, light management techniques using textured surfaces, similar to those used in established solar cell technologies, should be considered. Here, we apply a light managemen...

The perovskite / silicon-heterojunction (SHJ) tandem solar cell can theoretically overcome the efficiencies of the single junction solar cells with experimental results not far behind. Here, we use optical simulations to analyze the potential of such currently feasible monolithic perovskite / SHJ tandem devices. We consider three different device d...

Device modelling and characterization are indispensable tools in the design of photovoltaic devices. In the contribution we present two challenging issues related to accurate modelling and efficient characterization of light scattering at nanotextured interfaces or other nanophotonic structures used in solar cell technologies. The model based on fi...

A novel angular resolved scattering system for measurements of spatial angular distribution function (3D ADF) of scattered or emitted light using a digital camera is presented. 3D ADF is determined from the digital image captured from a transmissive flat screen. With the developed camera-based system we can quantify transmitted or reflected light s...

We present a system for the measurement of the three-dimensional (3D) angular distribution function (ADF) of scattered or emitted light using a digital camera. The 3D ADF can be determined from the digital image captured from a reflective flat screen. With the developed camera-based system we can quantify the transmitted light scattered by textured...

The conversion efficiency of solar energy into electrical energy is the most important parameter when discussing solar cells, photovoltaic (PV) modules or PV power plants. So far many papers have been written to address the limiting efficiency of solar cells, the theoretical maximum conversion efficiency an ideal solar cell could achieve. However,...