We compare the dark current-voltage (IV) characteristics of three different thin-film solar cell types: hydrogenated amorphous silicon (a-Si:H) p-i-n cells, organic bulk heterojunction (BHJ) and Cu(In,Ga)Se2 (CIGS) cells. All device types exhibit a significant shunt leakage current at low forward bias (V<∼0.4) reverse bias, which cannot be explained by classical diode model. This parasitic exhibits non-Ohmic behavior, as opposed to traditional constant resistance model for...

We analyze the problem of partial shading in monolithically integrated thin-film photovoltaic (TFPV) modules, and explore how shape size shadows dictate their performance reliability. focus on aspects unique to monolithic TFPV, arising from thin long rectangular series-connected cells, with covering only a fraction cell area. Using calibrated 2-D circuit simulations, we show that due shape, unshaded portion partially shaded experiences higher heat dissipation redistribution voltages currents...

Thin-film solar cells often show a crossover between the illuminated and dark I-V characteristics. Several device specific reasons for exist have been discussed extensively. In this paper, we that low contact-to-contact built-in potential can produce voltage-dependent photocurrent leads to at voltage is almost exactly potential. This mechanism in absence of carrier trapping or recombination. It be contributing factor crossover, but when an anomalously exists, it dominant factor. Using...

Parasitic shunt formation is an important cause of variability and module efficiency loss in all photovoltaic technologies. In this letter, we quantify the nature four major thin film (TFPV) technologies, namely, amorphous silicon (a-Si:H), organic (OPV), Cu(In,Ga)SSe (CIGS), CdTe. We analyze a wide variety datasets to show that current exhibits robust universal log-normal behavior for these affirm conclusion by rigorous statistical analysis available data. use equivalent circuit simulations...

In this letter, we investigate the nature of shunt leakage currents in large-area (on order square centimeters) thin-film a-Si:H p-i-n solar cells and show that it is characterized by following universal features: (1) voltage symmetry; (2) power-law dependence; (3) weak temperature dependence. The symmetry offers a robust empirical method to isolate diode current from measured "shunt-contaminated" forward dark IV. We find space-charge-limited provides best qualitative explanation for...

In this paper, we will focus on the problem of modeling global or die-to-die variation in semiconductor devices. We demonstrate that process corner-based approach for variation, which has been dominant design validation, fundamental limitations predicting circuit performance variation. then show how a full statistical model can accurately predict behavior and discuss some challenges moving from to simulations.

With continued scaling of CMOS technology, numerous concerns have been raised about random telegraph noise (RTN) possibly matching or exceeding the process variation in threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> )[1], [2]. These studies are usually limited by small sample size measurements, relying on modeling for projecting to high sigma. In this work, we use a modified ring oscillator (RO) circuit measure RTN...

We describe a comprehensive study of intrinsic reliability issue arising from partial shadowing photovoltaic panels (e.g., leaf fallen on it, nearby tree casting shadow, etc.). This can cause the shaded cells to be reverse biased, causing dark current degradation. In this paper, (1) we calculate statistical distribution bias stress various shading configurations, (2) identify components current, and provide scheme isolate them, (3) characterize effect a-Si:H p-i-n cells, (4) finally, combine...

In this paper, we develop an end-to-end modeling framework to explore how various multiscale phenomena in solar cells translate from materials module level. Specifically, the model captures physics related 1) pressure-dependent grain growth of polycrystalline thin films (nanometers micrometers), 2) averaging effects grain-size distribution at centimeter scale, and 3) parasitic series shunt resistance distributions on efficiency thin-film cell modules (centimeter meter scale). As idealized...

We present an end-to-end modeling framework, spanning the device, module and also system levels, for analyzing thin film photovoltaics (PV). This approach is based on embedding a detailed, statistically relevant, physics equivalent circuit into array level simulations. enables us to analyze key variability reliability issues in PV, allows interpret their effect process yield intrinsic lifetimes. Our results suggest that time-zero gap between cell efficiencies, concern thin-film can be...

Abstract Partial shading in photovoltaic modules is an important reliability and performance concern for all technologies. In this paper, we show how cell geometry can be used as a design variable improved shade tolerance monolithic thin film (TFPV). We use circuit simulations to illustrate the geometrical aspects of partial typical TFPV with rectangular cells, formulate rules tolerant design. that problem overcome by modifying shape orientation, while preserving module output...

In this paper, we present a physical model of the non-Ohmic shunt current I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SH</sub> in amorphous silicon (a-Si:H) p-i-n solar cells and validate it with detailed measurements. This is based on space-charge-limited (SCL) transport through localized p-i-p paths. These paths can arise from n-contact metal incorporation a-Si:H layer, causing (n)a-Si:H to be counterdoped p-type. The not only explains...

The gap between cell and module efficiency is a major challenge for all photovoltaic (PV) technologies. For monolithic thin-film PV modules, significant fraction of this has been attributed to parasitic shunts other defects, distributed across the module. In paper, we show that it possible contain or isolate these using state-of-the-art laser scribing processes, after fabrication series-connected finished. We discuss three alternatives, quantify performance gains each technique. demonstrate...

In this paper, we have discussed three intrinsic reliability issues of thin-film -Si:H solar cells; space charge limited shunt conduction through localized metal-semiconductor-metal structures; shadow degradation in series connected cells a module, and light induced degradation. Despite their distinct external manifestation, these appear to share common physical phenomena. For example, the may be related because they are described by very similar time-exponents (see Fig. 4c 6a). While...

Advancements in thin film Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ZnSn(S xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> Se xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> ) xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> (CZTSSe) solar cells have recently achieved power conversion efficiencies >;10%, indicating the potential of this low cost, earth abundant material system as a viable alternative to CIGS and CdTe...

Partial shading in thin film solar panels can result reverse bias stress across shaded cells. Therefore, it is important to understand the effect of such commercially competitive PV technologies as CIGS. In this paper, we systematically investigate moderate on solution-processed CIGS We subject cells varying degrees biases and continuously monitor impact dark current. also explore relaxation behavior current following passive storage long term shadow power output cell. find that affects only...

We analyze the problem of partial shading thin film photovoltaic (TFPV) panels, using full two dimensional circuit simulations. By accounting for panel structure and typical array configurations, we can accurately account effect various configurations at cell level. demonstrate limitation external bypass diodes in protecting shaded cells from reverse breakdown, explore whole range scenarios their impact on stress experienced by cells. Based analysis, identify key aspects problem, formulate...

In this paper, we develop a multi-scale, hierarchical cell-to-module modeling approach to interpret and predict the effects of average grain size distribution on cell efficiency polycrystalline thin film solar cells, specifically, that close space sublimated (CSS) CdTe. Our results explain why (1) increasing improves performance, (2) performance saturates beyond critical size, (3) effect is averaged over larger length-scales, therefore, (4) observed empirical module efficacy must be...

Partial shading in photovoltaic modules is an important reliability and performance concern for all technologies. In this paper, we show how cell geometry can be used as a design variable improved resilience towards partial monolithic thin film (TFPV) modules. We use circuit simulations to illustrate the geometrical aspects of typical TFPV with rectangular cells, formulate rules shade tolerant design. that problem overcome by modifying shape orientation, while preserving module output...

We present a physical model of non-ohmic shunt current in a-Si:H p-i-n solar cells, and validate it with detailed measurements. This is based on space-charge-limited (SCL) transport through localized p-i-p paths, which can arise from contact metal incorporation layer. explains both the electrical characteristics metastable switching behavior shunts within an integrated framework. first verify SCL using simulations statistically robust measurements, then use this picture to analyze our...