SPLTRAK Abstract Submission
Simulation-Based Determination of Shockley-Read-Hall Recombination Lifetimes in Group-V Doped P-N Junction CdTe Devices
Alexandra M. Bothwell& Darius Kuciauskas
National Renewable Energy Laboratory, Golden, CO, United States

Carrier recombination is a significant limiting mechanism in efficiency development in CdTe-based photovoltaic devices. Therefore, it is necessary to quantify bulk lifetimes for targeted improvement in devices. Time-resolved photoluminescence (TRPL) measurements on double heterostructures with no space-charge field are often used for bulk lifetime determination, while such determination on completed devices has not been consistently demonstrated. In group-V doped CdTe solar cells with hole density >1014 cm-3 and concomitantly stronger space charge fields, determination of bulk lifetime is both necessary and uncertain. In this work simulated TRPL decays and recombination rate components are analyzed for CdTe-based device structures when hole density is ~1015 cm-3, typical for high-efficiency bilayer absorber (CdSeTe/CdTe:As) solar cells fabricated at Colorado State University. We demonstrate that an effective Shockley-Read Hall recombination lifetime (front, bulk, and back) can be determined in devices with a p-n junction. Results support earlier reported >3 µs lifetime attribution to excellent bulk properties and interface passivation and should enable higher open circuit voltages.