Direct probing Se spatial distribution in Cu(In Ga1−)Se2 solar cells: A key factor to achieve high efficiency performance

Lin, Tzu-Chun; Chen, Chia‐Hsiang; Huang, Wei‐Chih; Ho, Wei-Hao; Wu, Yi-Chia; Lai, Chih‐Huang

doi:10.1016/j.nanoen.2015.11.003

Cited by 17 publications

(14 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The effective doping concentration, N CV , extracted from this curve was 5.53 × 10 15 /cm 3 , which falls within a similar range to the values reported for the most efficient devices . In the Se‐deficient CIGS absorber layer, deep level defects with activation energies of 300 meV or more are generated, which reduces the minority carrier lifetime or causes severe J‐V curve distortion, such as roll‐over . Furthermore, a post‐heat treatment for the supply of alkali elements or an additional selenization heat treatment at a low temperature of 400°C or lower must be applied to remove the roll‐over and passivate the deep level defects .…”

Section: Resultssupporting

confidence: 75%

“…In the Se‐deficient CIGS absorber layer, deep level defects with activation energies of 300 meV or more are generated, which reduces the minority carrier lifetime or causes severe J‐V curve distortion, such as roll‐over . Furthermore, a post‐heat treatment for the supply of alkali elements or an additional selenization heat treatment at a low temperature of 400°C or lower must be applied to remove the roll‐over and passivate the deep level defects . In contrast to the process complexity described earlier, the NFS used in this study for the synthesis of Se sufficient CIGS is a simple process and provides a new Se vapor‐based process technology that can replace the H 2 Se‐based selenization process.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Two‐step selenization using nozzle free Se shower for Cu(In,Ga)Se₂ thin film solar cell

Song

Kang

Baek

et al. 2017

Progress in Photovoltaics

View full text Add to dashboard Cite

The production of commercialized Cu(In,Ga)(S,Se) 2 (CIGS) photovoltaic absorber layers uses expensive H 2 Se gas with a high utility cost. To reduce the manufacturing cost of CIGS photovoltaic modules, a process technology capable of supplying Se vapor uniformly over a large area is required to replace H 2 Se. In this study, a nozzle-free Se shower was implemented using a porous material to pass Se vapor while confining liquid Se, and the highly effective selenization of the CuInGa precursor was performed. The nozzle-free Se-shower vehicle could be mounted in a commercial rapid thermal process chamber. The chamber pressure and the temperatures of the shower module and substrate, which were controlled independently by the upper and lower heaters, respectively, were varied to control the amount of Se supplied during the entire selenization reaction in real time. In particular, the precursor should be soaked with a sufficient amount of Se at a relatively low substrate temperature of 300°C or less to obtain a good quality absorber. In addition, at a chamber pressure of 100 Torr during the soaking stage, the Ga content in the surface region of the absorber increased considerably with a concomitant improvement in the open-circuit voltage. The highest performance obtained using this method was an open-circuit voltage of 0.638 V, short-circuit current density of 34 mA/cm 2 , fill factor of 67.2%, and an active area efficiency of 14.57%. This performance is very high compared with other CIGS solar cells manufactured by a 2-step process using Se vapor.

show abstract

Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Two‐step selenization using nozzle free Se shower for Cu(In,Ga)Se₂ thin film solar cell

Song

Kang

Baek

et al. 2017

Progress in Photovoltaics

View full text Add to dashboard Cite

show abstract

“…This is quite different from coevaporation or postselenization processes. A deficient supply of Se results in the formation of V Se and In Cu donor defects in CIGS thin films, which is detrimental to cell performance . To overcome these issues with Se deficiency, additional supply of Se through postselenization in either a Se or H 2 Se atmosphere is usually required .…”

Section: Introductionmentioning

confidence: 99%

Over 14% Efficiency of Directly Sputtered Cu(In,Ga)Se₂ Absorbers without Postselenization by Post‐Treatment of Alkali Metals

Hsu

Wei

et al. 2017

Advanced Energy Materials

Self Cite

View full text Add to dashboard Cite

junction quality, thus increasing open circuit voltage (V oc ) and fill factor (FF). It has also been observed that KF-PDT allows a steeper Ga gradient [8] and a thinner CdS buffer layer [6,8] to be employed without having a negative impact on device performance; therefore, the short circuit current (J sc ) can be improved after optimizing Ga gradient and CdS thickness.Though the improvement in device parameters has been generally observed, the underlying mechanism of KF-PDT is still unclear. One possible reason for the improved junction quality is the formation of a Cu-depleted surface layer, which may enlarge the surface bandgap [9] and promote the in-diffusion of Cd [6] during buffer layer deposition. However, the formation of a Cu-depleted surface does not seem to be always observed. For example, Mansfield et al. have claimed that no Cudepleted surface formed on the selenized CIGS after KF-PDT. [10] Another interesting observation is the reduction of Na content in CIGS after KF-PDT, nevertheless the consequences of which have not yet been discussed in literature. Further investigation is still required to fully understand the effects of KF-PDT.The research into CIGS deposited by three-stage coevaporation or two-step processes (metal deposition and postselenization) continues to advance in the pursuit of mass production and low-cost processing. In addition, various fabrication processes of CIGS thin films have been demonstrated and continue to be developed, for example, fabrication from electrodeposited [11] or nanoparticle-based [12] precursor layers. In these processes, however, selenization is indispensable. The need for a postselenization process inevitably increases production costs. Some researchers have attempted to eliminate this unfavorable and time-consuming process. For example, in a hydrazine-based process, device-quality CIGS absorbers were obtained by annealing the spin-coated precursors in an inert atmosphere, yielding cell efficiency of over 15%. [13] One of the key factors of eliminating selenization in the hydrazine-based process is that extra Se can be added into the precursor ink so extra Se in the atmosphere is not required during annealing. [14] However, the main disadvantage of the hydrazine-based process is its toxicity and instability.Directly sputtering from a single CIGS target is another promising process that could produce efficient CIGS absorbers Direct sputtering of a single quaternary Cu(In,Ga)Se 2 (CIGS) target without postselenization is a promising approach to fabricating CIGS absorbers. However, the device efficiency of the quaternary-sputtered CIGS is limited to 10%-11% due to the low and uncontrollable Se supply during the quaternary sputtering process. Here, an enhanced efficiency of 14.1% is reported by directly sputtering from a CIGS target without extra Se supply followed by sequential postdeposition treatments (PDT) of NaF and KF. The effects of different post-treatments of alkali metals on quaternary-sputtered CIGS thin films are discussed in detail. A Cu-depleted su...

show abstract

“…Figure a shows an example of minority carrier lifetime measurements using TRPL with a pulsed laser at a wavelength of 638 nm. [ 99 ] TRPL signals for postselenization‐treated CIGS films at different temperatures are measured. The decay characteristics for the PL intensity are presented in Figure 9a, and the minority carrier lifetime for each sample is derived from the curves.…”

Section: Characterization Of the Electrical Properties Of A Devicementioning

confidence: 99%

Toward Understanding Chalcopyrite Solar Cells via Advanced Characterization Techniques

Bae

Kim

Lee

et al. 2022

Adv Materials Inter

View full text Add to dashboard Cite

Figure 3. a) Schematic of a SAXS transmission geometry, with q i and q f denoting the incident and scattered beam wave vector, respectively. b) SEM and STEM cross-sectional images; reproduced with permission. [17] Copyright 2020, Wiley-VCH and c) SAXS profiles for U-CIGS, BK-CIGS, and SK-CIGS films. The dotted arrows denote the peak positions of the SAXS profiles at which the domain spacing is estimated. Reproduced with permission. [17]

show abstract

Direct probing Se spatial distribution in Cu(In Ga1−)Se2 solar cells: A key factor to achieve high efficiency performance

Cited by 17 publications

References 40 publications

Two‐step selenization using nozzle free Se shower for Cu(In,Ga)Se₂ thin film solar cell

Two‐step selenization using nozzle free Se shower for Cu(In,Ga)Se₂ thin film solar cell

Over 14% Efficiency of Directly Sputtered Cu(In,Ga)Se₂ Absorbers without Postselenization by Post‐Treatment of Alkali Metals

Toward Understanding Chalcopyrite Solar Cells via Advanced Characterization Techniques

Contact Info

Product

Resources

About

Direct probing Se spatial distribution in Cu(In Ga1−)Se2 solar cells: A key factor to achieve high efficiency performance

Cited by 17 publications

References 40 publications

Two‐step selenization using nozzle free Se shower for Cu(In,Ga)Se2 thin film solar cell

Two‐step selenization using nozzle free Se shower for Cu(In,Ga)Se2 thin film solar cell

Over 14% Efficiency of Directly Sputtered Cu(In,Ga)Se2 Absorbers without Postselenization by Post‐Treatment of Alkali Metals

Toward Understanding Chalcopyrite Solar Cells via Advanced Characterization Techniques

Contact Info

Product

Resources

About

Two‐step selenization using nozzle free Se shower for Cu(In,Ga)Se₂ thin film solar cell

Two‐step selenization using nozzle free Se shower for Cu(In,Ga)Se₂ thin film solar cell

Over 14% Efficiency of Directly Sputtered Cu(In,Ga)Se₂ Absorbers without Postselenization by Post‐Treatment of Alkali Metals