The roles of carrier concentration and interface, bulk, and grain-boundary recombination for 25% efficient CdTe solar cells

Abstract

CdTe devices have reached efficiencies of 22% due to continuing improvements in bulk material properties, including minority carrier lifetime. Device modeling has helped to guide these device improvements by quantifying the impacts of material properties and different device designs on device performance. One of the barriers to truly predictive device modeling is the interdependence of these material properties. For example, interfaces become more critical as bulk properties, particularly, hole density and carrier lifetime, increase. We present device-modeling analyses that describe the effects of recombination at the interfaces and grain boundaries as lifetime and doping of the CdTe layer change. The doping and lifetime should be priorities for maximizing open-circuit voltage (Voc) and efficiency improvements. However, interface and grain boundary recombination become bottlenecks for device performance at increased lifetime and doping levels. This work quantifies and discusses these emerging challenges for next-generation CdTe device efficiency.

Stable monolayer α-phase of CdTe: strain-dependent properties

“…28 Therefore, this material has an extensive usage in optoelectronic device applications such as photo-detectors, infrared and gamma-ray detectors. [29][30][31][32][33] Beyond its bulk form, dimensionally reduced CdTe structures, e.g. quantum dots and rods, 34 have attracted great attention due to their composition-and size-dependent absorption and emission spectrum.…”

Charged Grain Boundaries and Carrier Recombination in Polycrystalline Thin-Film Solar Cells

“…This finding has renewed the impetus to understand and mitigate the impact of grain boundaries on V oc . Most previous theoretical works in this direction have consisted of numerical simulations [5][6][7][8]11]. Alternately, analytical models offer a concise, quantitative description of system behavior while providing further insight.…”

Radiative Efficiency and Charge‐Carrier Lifetimes and Diffusion Length in Polycrystalline CdSeTe Heterostructures

“…Direct‐bandgap thin‐film PV materials, especially CdTe, have superior temperature and spectral coefficients, and they have demonstrated low degradation . For CdTe solar cells, higher efficiency targets can be met if sources of nonradiative recombination can be identified and minimized. Record‐efficiency CdTe solar cells have open‐circuit voltage V OC = 880 mV, which is only 76.1% of the Shockley–Queisser (SQ) limit ( V OC,SQ = 1157 mV for the 1.42 eV bandgap, Supplementary Information in the study by Guillemoles et al).…”