time-resolved pl

**TRPL** (Time-Resolved Photoluminescence) is a **technique that measures the temporal decay of photoluminescence after pulsed laser excitation** — extracting carrier lifetimes, recombination mechanisms, and surface recombination velocities from the decay dynamics. **How Does TRPL Work?** - **Pulsed Laser**: Short pulse (fs-ps) creates carriers at $t = 0$. - **Decay**: Monitor PL intensity vs. time as carriers recombine. - **TCSPC**: Time-Correlated Single Photon Counting provides ps-level time resolution. - **Streak Camera**: Provides simultaneous spectral and temporal resolution. **Why It Matters** - **Carrier Lifetime**: The most direct measurement of minority carrier lifetime in bulk and thin-film semiconductors. - **Solar Cells**: Carrier lifetime determines photovoltaic efficiency — TRPL is the standard characterization. - **Surface Recombination**: By comparing TRPL on passivated vs. unpassivated surfaces, extract surface recombination velocity. **TRPL** is **the carrier lifetime clock** — measuring how long excited carriers survive before recombining, the key metric for semiconductor quality.