2.3 Carrier Generation and Recombination Carrier generation is a process where electron-hole pairs are created by exciting an electron from the valence band of the semiconductor to the conduction band, thereby creating a hole in the valence band.
![Carrier Carrier](http://ecee.colorado.edu/~bart/book/generati.gif)
We use flash-photolysis time-resolved microwave conductivity experiments ( FP-TRMC) and femtosecond–nanosecond pump–probe transient absorption spectroscopy to investigate photoinduced carrier generation and recombination dynamics of a trilayer cascade heterojunction composed of poly(3-hexylthiophene) (P3HT), titanyl phthalocyanine (TiOPc), and fullerene (C 60). Carrier generation following selective photoexcitation of TiOPc is independently observed at both the P3HT/TiOPc and TiOPc/C 60 interfaces. The transient absorption results indicate that following initial charge generation processes to produce P3HT •+/TiOPc •– and TiOPc •+/C 60 •– at each interface from (P3HT/TiOPc*/C 60), the final charge-separated product of (P3HT •+/TiOPc/C 60 •–) is responsible for the long-lived photoconductance signals in FP-TRMC. At the P3HT/TiOPc interface in both P3HT/TiOPc and P3HT/TiOPc/C 60 samples, the electron transfer appears to occur only with the crystalline (weakly coupled H-aggregate) phase of the P3HT. • Ca' Foscari University of Venice • Cagliari State University • Free University of Bolzano • Politecnico di Bari • Scuola Superiore Sant'Anna • University of Bologna • University of Camerino • University of Genoa • University of Messina • University of Naples Federico II • University of Padova • University of Palermo • University of Parma • University of Pavia • University of Perugia • University of Pisa • University of Roma TRE • University of Rome Tor Vergata • University of Siena • University of Verona. • Agilent Technologies Inc • Agnes Scott College • Ajman University of Science and Technology • AkzoNobel • Aligarh Muslim University • Anonymous Petcare • Aston University • Azusa Pacific (APU) & Los Angeles Pacific (LAPU) University • BP International • BRAC University • Bar-Ilan University • Baylor Health Sciences Library • Birkbeck College • Bridgend College • Bristol-Myers Squibb • Calico Life Sciences LLC • Case Western Reserve University • Celgene • Columbus State University • Coventry University • DSM N.V.