Thin-film (Sb,Bi)2Se3 Semiconducting Layers with Tunable Band Gaps Below 1 eV for Photovoltaic Applications

in Physical Review Applied (2020), 14

Bulk and surface recombination properties in thin film semiconductors with different surface treatments from timeresolved photoluminescence measurements

in Scientific Reports (2019), 9

The knowledge of minority carrier lifetime of a semiconductor is important for the assessment of its quality and design of electronic devices. Time-resolved photoluminescence (TRPL) measurements offer the ... [more ▼]

The knowledge of minority carrier lifetime of a semiconductor is important for the assessment of its quality and design of electronic devices. Time-resolved photoluminescence (TRPL) measurements offer the possibility to extract effective lifetimes in the nanosecond range. However, it is difficult to discriminate between surface and bulk recombination and consequently the bulk properties of the semiconductor cannot be estimated reliably. Here we present an approach to constrain systematically the bulk and surface recombination parameters in semiconducting layers and reduces to finding the roots of a mathematical function. This method disentangles the bulk and surface recombination based on TRPL decay times of samples with different surface preparations. The technique is exemplarily applied to a CuInSe2 and a back-graded Cu(In,Ga)Se2 compound semiconductor, and upper and lower bounds for the recombination parameters and the mobility are obtained. Sets of calculated parameters are extracted and used as input for simulations of photoluminescence transients, yielding a good match to experimental data and validating the effectiveness of the methodology. A script for the simulation of TRPL transients is provided. [less ▲]

Alkali treatments of Cu(In,Ga)Se2 thin‐film absorbers and their impact on transport barriers

in Progress in Photovoltaics (2018)

Impact of annealing on electrical properties of Cu2ZnSnSe4 absorber layers

in Journal of Applied Physics (2016), 120

ELECTRICAL CHARACTERIZATION OF KESTERITE THIN FILM ABSORBERS AND SOLAR CELLS

Doctoral thesis (2015)

Highly conductive ZnO films with high near infrared transparency

in Progress in Photovoltaics: Research and Applications (2015)

We present an approach for deposition of highly conductive nominally undoped ZnO films that are suitable for the n-type window of low band gap solar cells. We demonstrate that low-voltage radio frequency ... [more ▼]

We present an approach for deposition of highly conductive nominally undoped ZnO films that are suitable for the n-type window of low band gap solar cells. We demonstrate that low-voltage radio frequency (RF) biasing of growing ZnO films during their deposition by non-reactive sputtering makes them as conductive as when doped by aluminium (ρ≤1·10−3Ω cm). The films prepared with additional RF biasing possess lower free-carrier concentration and higher free-carrier mobility than Al-doped ZnO (AZO) films of the same resistivity, which results in a substantially higher transparency in the near infrared region (NIR). Furthermore, these films exhibit good ambient stability and lower high-temperature stability than the AZO films of the same thickness. We also present the characteristics of Cu(InGa)Se2, CuInSe2 and Cu2ZnSnSe4-based solar cells prepared with the transparent window bilayer formed of the isolating and conductive ZnO films and compare them to their counterparts with a standard ZnO/AZO bilayer. We show that the solar cells with nominally undoped ZnO as their transparent conductive oxide layer exhibit an improved quantum efficiency for λ > 900 nm, which leads to a higher short circuit current density JSC. This aspect is specifically beneficial in preparation of the Cu2ZnSnSe4 solar cells with band gap down to 0.85 eV; our champion device reached a JSC of nearly 39 mAcm−2, an open circuit voltage of 378 mV, and a power conversion efficiency of 8.4 %. [less ▲]

The band gap of Cu2ZnSnSe4: Effect of order-disorder

in Applied Physics Letters (2014), 105

Different Bandgaps in Cu2ZnSnSe4 : a high temperature coevaporation study

in IEEE Journal of Photovoltaics (2014)

Role of high series resistance in admittance spectroscopy of kesterite solar cells

Scientific Conference (2013)

Cu-rich precursors improve kesterite solar cells

in Advanced Energy Materials (2013), 4