  We demonstrate direct cooling of gaseous formaldehyde (H2CO) to the
microkelvin regime. Our approach, optoelectrical Sisyphus cooling, provides a
simple dissipative cooling method applicable to electrically trapped dipolar
molecules. By reducing the temperature by three orders of magnitude and
increasing the phase-space density by a factor of ~$10^4$ we generate an
ensemble of $3\cdot10^5$ molecules with a temperature of about 420\mu K,
populating a single rotational state with more than 80% purity.
